Phthalocyanine crystal, and electrophotographic photoreceptor, electrophotographic photoreceptor cartridge and image-forming device using the same

ABSTRACT

Provided is an excellent phthalocyanine crystal having high sensitivity and little fluctuation in sensitivity for a humidity change in a use environment and applicable to the martial for solar battery, electronic paper, electrophotographic photoreceptor, etc. Namely, phthalocyanine crystal obtained by bringing a phthalocyanine crystal precursor into contact with an aromatic aldehyde compound to convert the crystal form. Also, provided is an electrophotographic photoreceptor that not only exhibits high sensitivity but also has little fluctuation in sensitivity for a humidity change in a use environment. Further, provided is an electrophotographic photoreceptor cartridge and an image-forming device, both of which can produce a stable quality images for a humidity change in a use environment by using the electrophotographic photoreceptor.

This application is a Divisional of U.S. application Ser. No.12/293,830, filed on Nov. 26, 2008, which is a National Stage ofPCT/JP2007/055744, filed Mar. 20, 2007.

TECHNICAL FIELD

The present invention relates to a phthalocyanine crystal obtained byconverting the crystal form of a phthalocyanine crystal precursor aswell as an electrophotographic photoreceptor, an electrophotographicphotoreceptor cartridge, and an image-forming device using thephthalocyanine crystal. Particularly, it relates to an excellentphthalocyanine crystal which is highly sensitive to LED light andsemiconductor laser light, has little fluctuation in sensitivity for ahumidity change in a use environment, and applicable to the material forsolar battery, electronic paper, electrophotographic photoreceptor,etc., as well as an electrophotographic photoreceptor, anelectrophotographic photoreceptor cartridge, and an image-forming devicethat not only exhibits high sensitivity but also has little fluctuationin sensitivity for a humidity change in a use environment.

BACKGROUND ART

Recently, organic optical devices capable of being utilized in solarbattery, electronic paper, electrophotography, etc have been intensivelyinvestigated. Of these, especially, electrophotographic technology hasbeen widely used and applied not only in the field of copying machinesbut also in the field of various printers and printing machines inrecent years because the technology is excellent in immediacy and canproduce high-quality images.

As an electrophotographic photoreceptor (hereinafter, optionallyabbreviated as “photoreceptor”) that is the core of theelectrophotography technology, photoreceptors using inorganicphotoconductors such as selenium, arsenic-selenium alloy, and zinc oxidehave been conventionally employed but recently, the mainstream becomesthe photoreceptors using organic photoconductive materials, which havethe advantages of entailing no pollution, ensuring easy film formationand manufacture, having high freedom in material selection andcombination, etc.

The sensitivity of the electrophotographic photoreceptors using organicphotoconductive materials varies depending on the wavelength of exposurelight and the kind of the charge generation substance.

As the charge generation substance having sensitivity to long-wavelengthlight of 600 to 800 nm, phthalocyanine compounds have been attractingattention. Especially, intensive studies have been conducted onmetal-containing phthalocyanines such as chloroaluminum phthalocyanine,chloroindium phthalocyanine, oxyvanadium phthalocyanine, hydroxygalliumphthalocyanine, chlorogallium phthalocyanine, magnesium phthalocyanine,and oxytitanium phthalocyanine, as well as metal-free phthalocyaninesand the likes.

With regard to the phthalocyanine compounds, it is reported that even ifthe structure of the individual molecule is identical, a phthalocyaninecompound may different in charge generation efficiency according to theregularity (crystal form) in arrangement of crystal, which is anagglomerate of molecules (see Non-Patent Documents 1 and 2).

In recent years, as the electrophotographic process in copying machines,laser printers, plain paper faxes, and the like has been advanced to behigh-speed and full-colored one, it is essential to have highsensitivity and high-speed responding ability, so that it is inevitableto develop a more highly sensitive charge generation substance.

For high sensitivity, it is essential to have charge generationsubstances having a high charge generating ability. Of these, eagerstudies have been conducted on oxytitanium phthalocyanine exhibitinghigh sensitivity to LD exposure that is the current mainstream. Theabove oxytitanium phthalocyanine is known to show crystal polymorphism.As known crystal forms, there have been reported a large number ofcrystal forms such as α-form (see Patent Document 1), β-form (see PatentDocument 2), C-form (see Patent Document 3), D-form (see Patent Document4), Y-form (see Patent Document 5), M-form (see Patent Document 6),M-α-form (see Patent Document 7), and I-form (see Patent Document 8).

Among these crystal forms, a crystal form having a main peak at Braggangle (2θ±0.2°) of 27.2° toward CuKα characteristic X-ray (wavelength1.541 angstrom) (hereinafter, optionally referred to as “particularcrystal form” in some cases) is known to exhibit high quantum efficiencyand high sensitivity.

Moreover, other than the crystal composed of oxytitanium phthalocyaninemolecule alone, mixed crystals composed of oxytitanium phthalocyanineand the other phthalocyanine or other pigment or the like are alsowidely known to form the above particular crystal form and exhibit highsensitivity (see Patent Document 9).

The above phthalocyanine crystals containing oxytitanium phthalocyanineshaving the particular crystal form are known to have very highsensitivity. It is considered that the high sensitivity is exhibitedbecause water molecules are present in the crystals and function assensitizers. However, the water molecules acting as sensitizers freelycome in and out the crystals depending on humidity change in theenvironment of the crystals and hence the phthalocyanine crystals have adisadvantage that the water molecules may be eliminated from thecrystals and bring about decrease in sensitivity when the humidity inthe environment of the crystals becomes low.

The disadvantage that the decrease in sensitivity by the elimination ofwater molecules with the humidity decrease may result in a problem of adifference between the densities of the resulting images outputted undera usual humidity condition and under a dry and low humidity condition inthe case where the phthalocyanine crystals are used as photographicphotoreceptors in laser printers, copying machines, and the like.Particularly, in full-color laser printers and copying machines comeinto wide use in recent years, the decrease in image density remarkablyappears in color tone change of full-color images and the like and hencebecomes a serious problem.

As explained above, phthalocyanine crystals containing oxytitaniumphthalocyanines having the particular crystal form exhibit highsensitivity but have a problem that the properties remarkably changedepending on change in a use environment.

On the other hand, there has been reported V-form hydroxygalliumphthalocyanine as a charge generation substance with little change inelectrical properties for a humidity change. This V-form hydroxygalliumphthalocyanine has an advantage of very little fluctuation insensitivity for a humidity change but is poor in sensitivity as comparedwith the oxytitanium phthalocyanine having a particular crystal form andhence it is current situation that electrical properties areinsufficient for the requirement for recent high-speed image-formingdevices where a number of sheets are printed per unit time in full color(see Non-Patent Document 3).

Furthermore, in order to suppress the sensitivity change of theoxytitanium phthalocyanine having a particular crystal form for ahumidity change, a method of adding a moisturizing agent to the chargegeneration layer has been reported (see Patent Documents 10 to 12).However, in these technologies, only humidity dependence according toresidual potential is improved but the sensitivity fluctuation for ahumidity change is not sufficiently improved. Since image deteriorationdepending on a humidity change tends to occur not in solid black imagesbut in halftone images, it is necessary to reduce fluctuation ofsensitivity. Actually, in a photo-induced discharge curve of theoxytitanium phthalocyanine having a particular crystal form, it isunderstood that fluctuation of potential part according to halftone(absolute value of potential is around from 100 to 300 V) is large for ahumidity change and thus it is still insufficient for the requirement ofreducing the potential fluctuation.

Non-Patent Document 1: Journal of the Society of Electrophotography ofJapan, Vol. 29, No. 3, pp. 250-258.

Non-Patent Document 2: Journal of the Society of Electrophotography ofJapan, Vol. 32, No. 3, pp. 282-289.

Non-Patent Document 3: Fuji Xerox Technical Report No. 12 1998

Patent Document 1: JP-A-61-217050

Patent Document 2: JP-A-62-67094

Patent Document 3: JP-A-63-366

Patent Document 4: JP-A-2-8265

Patent Document 5: JP-A-63-20365

Patent Document 6: JP-A-3-54265

Patent Document 7: JP-A-3-54264

Patent Document 8: JP-A-3-128973

Patent Document 9: JP-A-3-9962

Patent Document 10: JP-A-2003-207912

Patent Document 11: JP-A-2003-186217

Patent Document 12: JP-A-2003-215825

DISCLOSURE OF THE INVENTION Problems that the Invention is to Solve

The above phthalocyanine crystals showing the particular crystal form(the cases of the “phthalocyanine crystals” refer to all crystalscontaining phthalocyanine compounds including not only crystals composedof single phthalocyanine compound alone but also mixed crystals composedof two or more phthalocyanine compounds and mixed crystals composed ofphthalocyanine compound and the other molecule; the “phthalocyaninecompound” will be mentioned below) exhibit very high sensitivity. Thehigh sensitivity is exhibited because water molecules are present in thecrystals and function as sensitizers. However, the water moleculesacting as sensitizers freely come into the crystals and out from thecrystals depending on a humidity change in the environment of thecrystals and hence the phthalocyanine crystals have a problem that thewater molecules may be eliminated from the crystals and bring aboutdecrease in sensitivity when the humidity becomes low.

The problem that the decrease in sensitivity by the elimination of watermolecules with the humidity decrease may result in a problem of adifference between the densities of the resulting images outputted undera usual humidity condition and under a dry and low humidity condition inthe case where the phthalocyanine crystals having the particular crystalform are used as photographic photoreceptors in laser printers, copyingmachines, and the like. Particularly, in full-color laser printers andcopying machines come into wide use in recent years, the decrease inimage density remarkably appears as a color tone change of full-colorimages and the like and hence becomes a serious problem.

The above phthalocyanine crystal having the particular crystal form isproduced by bringing a precursor phthalocyanine into contact with aparticular compound to convert the crystal form. In the crystalform-converting step, the crystal form is constructed by the interactionbetween the compound molecule used and the phthalocyanine. On thisoccasion, depending on the compound used, the interaction with thephthalocyanine varies and thus various crystal forms and particle shapesare shown depending on the difference of production processes. Moreover,the properties as the electrophotographic photoreceptor, such as chargegenerating ability (sensitivity), charging property, and dark decay alsodepend on the production process and hence it is very difficult topredict the performance in advance.

As above, the above phthalocyanine crystals having the particularcrystal form exhibit high sensitivity but have a problem that theproperties remarkably change depending on a change in a use environment.As mentioned above, it is a current situation that anelectrophotographic photoreceptor having higher sensitivity and littlefluctuation in sensitivity for a humidity change in a use environmenthas been widely desired in recent mainstream laser printers, copyingmachines, and the like capable of printing a number of sheets per unittime in full color with high quality, but has not yet been developed.

The invention has been achieved in consideration of the above demands.Namely, an object of the invention is to provide a phthalocyaninecrystal having high sensitivity and having little fluctuation insensitivity for a humidity change in an use environment, to provide anelectrophotographic photoreceptor that not only exhibits highsensitivity but also has little fluctuation in sensitivity for ahumidity change in a use environment, and further to provide anelectrophotographic photoreceptor cartridge and an image-forming device,both of which can produce stable quality images for a humidity change ina use environment by using the electrophotographic photoreceptor.

Means for Solving the Problems

The present inventors have presumed that the compound used at theconversion of the crystal form of a phthalocyanine crystal precursor maydeeply participate in the fluctuation in sensitivity of the resultingelectrophotographic photoreceptor for a humidity change and, as a resultof the extensive studies for solving the above problems, the inventorshave found that phthalocyanine crystal obtained by converting thecrystal form of the phthalocyanine crystal precursor in the presence ofa particular compound has high sensitivity and also little fluctuationin sensitivity for a humidity change in a use environment and it is alsopossible to obtain an electrophotographic photoreceptor having highsensitivity and also little fluctuation in sensitivity for a humiditychange in a use environment. Thus, they have accomplished the invention.

Namely, the gist of the invention lies in a phthalocyanine crystal,which is obtained through a step of bringing a phthalocyanine crystalprecursor into contact with an aromatic aldehyde compound to convert thecrystal form.

The other gist of the invention lies in a phthalocyanine crystal, whichis obtained through a step of bringing a phthalocyanine crystalprecursor into contact with an organic compound having no functionalgroup showing acidity in the presence of at least one compound selectedfrom the group consisting of organic acids, organic acid anhydrides, andorganic acid esters having a heteroatom to convert the crystal form.

The still other gist of the invention lies in a phthalocyanine crystal,which is obtained through a step of bringing a phthalocyanine crystalprecursor into contact with an organic compound which is in a liquidstate under conditions of 1013 hPa and 25° C. and does not have afunctional group showing acidity in the presence of an aromatic compoundwhich is solid under conditions of 1013 hPa and 25° C. and has anelectron-withdrawing substituent to convert the crystal form.

The other gist of the invention lies in a phthalocyanine crystal, whichis obtained through a step of bringing a phthalocyanine crystalprecursor into contact with an aromatic compound having an oxygenatom-containing group and a halogen atom having an atomic weight of 30or more to convert the crystal form.

The above oxygen atom-containing group is preferably a group selectedfrom the group consisting of a carbonyl group-containing organic group,a nitro group, and an ether group.

The above step of converting the crystal form is preferably carried outin the presence of water.

Also, the phthalocyanine crystal is preferably a crystal containingoxytitanium phthalocyanine.

Moreover, the above phthalocyanine crystal preferably has a maindiffraction peak at Bragg angle) (2θ±0.2°) of 27.2° toward CuKαcharacteristic X-ray (wavelength 1.541 angstrom).

The other gist of the invention lies in an electrophotographicphotoreceptor comprising an electroconductive substrate and aphotosensitive layer formed on the substrate, wherein the photosensitivelayer contains the above phthalocyanine crystal.

The other gist of the invention lies in an electrophotographicphotoreceptor comprising:

a photosensitive layer having a film thickness of 35±2.5 μm, wherein ahalf-decay exposure E1/2 at a temperature of 25° C. and a relativehumidity of 50% rh satisfies the following expression (1), and anabsolute value of the difference in surface potential at the sameexposure does not exceed 50V in the range of the exposure of 0 to 10times the half-decay exposure E1/2 when a photo-induced discharge curveat a temperature of 25° C. and a relative humidity of 50% rh is comparedwith a photo-induced discharge curve at a temperature of 25° C. and arelative humidity of 10% rh:E1/2≦0.059  (1)where, in the formula (1), E1/2 represents exposure (μJ/cm²) of lighthaving a wavelength of 780 nm required for decaying the absolute value|V0| of the surface potential V0 of the photoreceptor from 550V to 275V;

a photosensitive layer having a film thickness of 30±2.5 μm formed onthe substrate, wherein a half-decay exposure E1/2 at a temperature of25° C. and a relative humidity of 50% rh satisfies the followingexpression (2) and an absolute value of the difference in surfacepotential at the same exposure does not exceed 50V in the range of theexposure of 0 to 10 times the half-decay exposure E1/2 when aphoto-induced discharge curve at a temperature of 25° C. and a relativehumidity of 50% rh is compared with a photo-induced discharge curve at atemperature of 25° C. and a relative humidity of 10% rh:E1/2≦0.061  (2)where, in the formula (2), E1/2 represents exposure (μJ/cm²) of lighthaving a wavelength of 780 nm required for decaying the absolute value|V0| of the surface potential V0 of the photoreceptor from 550V to 275V;

a photosensitive layer having a film thickness of 25±2.5 μm formed onthe substrate, wherein a half-decay exposure E1/2 at a temperature of25° C. and a relative humidity of 50% rh satisfies the followingexpression (3) and an absolute value of the difference in surfacepotential at the same exposure does not exceed 50V in the range of theexposure of 0 to 10 times the half-decay exposure E1/2 when aphoto-induced discharge curve at a temperature of 25° C. and a relativehumidity of 50% rh is compared with a photo-induced discharge curve at atemperature of 25° C. and a relative humidity of 10% rh:E1/2≦0.066  (3)where, in the formula (3), E1/2 represents exposure (μJ/cm²) of lighthaving a wavelength of 780 nm required for decaying the absolute value|V0| of the surface potential V0 of the photoreceptor from 550V to 275V;

a photosensitive layer having a film thickness of 20±2.5 μm formed onthe substrate, wherein a half-decay exposure E1/2 at a temperature of25° C. and a relative humidity of 50% rh satisfies the followingexpression (4) and an absolute value of the difference in surfacepotential at the same exposure does not exceed 50V in the range of theexposure of 0 to 10 times the half-decay exposure E1/2 when aphoto-induced discharge curve at a temperature of 25° C. and a relativehumidity of 50% rh is compared with a photo-induced discharge curve at atemperature of 25° C. and a relative humidity of 10% rh:E1/2≦0.079  (4)where, in the formula (4), E1/2 represents exposure (μJ/cm²) of lighthaving a wavelength of 780 nm required for decaying the absolute value|V0| of the surface potential V0 of the photoreceptor from 550V to 275V;or

a photosensitive layer having a film thickness of 15±2.5 μm formed onthe substrate, wherein a half-decay exposure E1/2 at a temperature of25° C. and a relative humidity of 50% rh satisfies the followingexpression (5) and an absolute value of the difference in surfacepotential at the same exposure does not exceed 50V in the range of theexposure of 0 to 10 times the half-decay exposure E1/2 when aphoto-induced discharge curve at a temperature of 25° C. and a relativehumidity of 50% rh is compared with a photo-induced discharge curve at atemperature of 25° C. and a relative humidity of 10% rh:E1/2≦0.090  (5)where, in the formula (5), E1/2 represents exposure (μJ/cm²) of lighthaving a wavelength of 780 nm required for decaying the absolute value|V0| of the surface potential V0 of the photoreceptor from 550V to 275V.

In any of the above electrophotographic photoreceptors, thephotosensitive layer preferably contains oxytitanium phthalocyanine.

Moreover, the other gist of the invention lies in an electrophotographicphotoreceptor cartridge comprising:

the above electrophotographic photoreceptor; and

at least one of

a charge unit for charging the electrophotographic photoreceptor,

an exposure unit for exposing the charged electrophotographicphotoreceptor to form an electrostatic latent image thereon,

a development unit for developing the electrostatic latent image formedon the electrophotographic photoreceptor, and

a cleaning unit for cleaning an upper side of the electrophotographicphotoreceptor.

Furthermore, the other gist of the invention lies in an image-formingdevice comprising:

the above electrophotographic photoreceptor; and

a charge unit for charging the electrophotographic photoreceptor,

an exposure unit for exposing the charged electrophotographicphotoreceptor to form an electrostatic latent image thereon, and

a development unit for developing the electrostatic latent image formedon the electrophotographic photoreceptor.

Advantages of the Invention

The phthalocyanine crystal of the invention has an advantage of havinghigh sensitivity and also little fluctuation in sensitivity for ahumidity change in a use environment.

Moreover, the electrophotographic photoreceptor of the invention has anadvantage of having high sensitivity and also little fluctuation insensitivity for a humidity change in a use environment.

Furthermore, the electrophotographic photoreceptor cartridge andimage-forming device of the invention has an advantage of capable ofproviding stable quality images for a humidity change in a useenvironment.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1]

FIG. 1 is a schematic view illustrating a composition of the substantialpart of one embodiment of the image-forming device of the invention.

[FIG. 2]

FIG. 2 illustrates an example of a powder X-ray diffraction spectrum ofa low-crystalline phthalocyanine.

[FIG. 3]

FIG. 3 illustrates an example of a powder X-ray diffraction spectrum ofa low-crystalline phthalocyanine.

[FIG. 4]

FIG. 4 illustrates an example of a powder X-ray diffraction spectrum ofan amorphous phthalocyanine.

[FIG. 5]

FIG. 5 illustrates an example of a powder X-ray diffraction spectrum ofan amorphous phthalocyanine.

[FIG. 6]

FIG. 6 is a powder XRD spectrum of the crystalline β-form oxytitaniumphthalocyanine obtained in Synthetic Example 1.

[FIG. 7]

FIG. 7 is a powder XRD spectrum of the low-crystalline oxytitaniumphthalocyanine obtained in Synthetic Example 2.

[FIG. 8]

FIG. 8 is a powder XRD spectrum of the phthalocyanine crystal (a crystalof oxytitanium phthalocyanine alone) obtained in Example 1.

[FIG. 9]

FIG. 9 is a powder XRD spectrum of the phthalocyanine crystal (a crystalof oxytitanium phthalocyanine alone) obtained in Example 2.

[FIG. 10]

FIG. 10 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 3.

[FIG. 11]

FIG. 11 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 4.

[FIG. 12]

FIG. 12 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 1.

[FIG. 13]

FIG. 13 is a powder XRD spectrum of the low-crystalline phthalocyanine(a composition containing oxytitanium phthalocyanine and metal-freephthalocyanine) obtained in Synthetic Example 3.

[FIG. 14]

FIG. 14 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 5.

[FIG. 15]

FIG. 15 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 6.

[FIG. 16]

FIG. 16 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 7.

[FIG. 17]

FIG. 17 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 8.

[FIG. 18]

FIG. 18 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Comparative Synthetic Example 2.

[FIG. 19]

FIG. 19 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 17.

[FIG. 20]

FIG. 20 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 18.

[FIG. 21]

FIG. 21 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 19.

[FIG. 22]

FIG. 22 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 20.

[FIG. 23]

FIG. 23 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 21.

[FIG. 24]

FIG. 24 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 22.

[FIG. 25]

FIG. 25 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 3.

[FIG. 26]

FIG. 26 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 4.

[FIG. 27]

FIG. 27 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 5.

[FIG. 28]

FIG. 28 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 6.

[FIG. 29]

FIG. 29 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 7.

[FIG. 30]

FIG. 30 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in ComparativeSynthetic Example 8.

[FIG. 31]

FIG. 31 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 23.

[FIG. 32]

FIG. 32 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 24.

[FIG. 33]

FIG. 33 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 25.

[FIG. 34]

FIG. 34 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Comparative Synthetic Example 9.

[FIG. 35]

FIG. 35 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Comparative Synthetic Example 10.

[FIG. 36]

FIG. 36 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Comparative Synthetic Example 11.

[FIG. 37]

FIG. 37 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Comparative Synthetic Example 12.

[FIG. 38]

FIG. 38 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 35.

[FIG. 39]

FIG. 39 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 64.

[FIG. 40]

FIG. 40 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 66.

[FIG. 41]

FIG. 41 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 67.

[FIG. 42]

FIG. 42 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 68.

[FIG. 43]

FIG. 43 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 69.

[FIG. 44]

FIG. 44 is a powder XRD spectrum of the phthalocyanine crystal (a mixedcrystal of oxytitanium phthalocyanine and metal-free phthalocyanine)obtained in Example 70.

[FIG. 45]

FIG. 45 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 128.

[FIG. 46]

FIG. 46 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 129.

[FIG. 47]

FIG. 47 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 130.

[FIG. 48]

FIG. 48 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 131.

[FIG. 49]

FIG. 49 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 132.

[FIG. 50]

FIG. 44 is a powder XRD spectrum of the phthalocyanine crystal (acrystal of oxytitanium phthalocyanine alone) obtained in Example 133.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   1 photoreceptor (electrophotographic photoreceptor)-   2 charging device (charging roller; charge unit)-   3 exposure device (exposure unit)-   4 developing device (development unit)-   5 transfer device-   6 cleaning device (cleaning unit)-   7 fixing device-   41 developing bath-   42 agitator-   43 feeding roller-   44 developing roller-   45 regulating member-   71 upper fixing member (fixing roller)-   72 lower fixing member (fixing roller)-   73 heating device-   T toner-   P recording paper (paper, medium)

Best Mode for Carrying Out the Invention

The present invention will be explained in detail hereinafter but theinvention should by no means be limited to the following explanation andcan be implemented with various variations within the range of the gist.

[I. Crystalline Phthalocyanine]

The phthalocyanine crystal of the invention is obtained through a stepof bringing a phthalocyanine crystal precursor into contact with aparticular compound to convert the crystal form (hereinafter optionallyreferred to as “crystal form-converting step”) in the presence of aparticular compound according to need.

The crystal form-converting step may be classified into the following(A) to (D) depending on the kind of the particular compound to bebrought into contact with the phthalocyanine crystal precursor(hereinafter optionally referred to as “contact compound for convertingthe crystal form”) and the particular compound to be present on thisoccasion according to need (hereinafter optionally referred to as“co-existing compound for converting the crystal form” and the contactcompound for converting the crystal form and the co-existing compoundfor converting the crystal form are optionally collectively referred toas “compound for converting the crystal form”).

(A) The crystal form is converted by bringing a phthalocyanine crystalprecursor into contact with an aromatic aldehyde compound. Namely, asthe contact compound for converting the crystal form, an aromaticaldehyde compound is used (hereinafter the aromatic aldehyde compound issometimes referred to as “compound (A) for converting the crystal form”.

(B) The crystal form is converted by bringing a phthalocyanine crystalprecursor into contact with an organic compound having no functionalgroup showing acidity (hereinafter optionally referred to as “non-acidicorganic compound”) in the presence of at least one compound selectedfrom the group consisting of organic acids, organic acid anhydrides, andorganic acid esters having a heteroatom (hereinafter optionally referredto as “particular organic acid compound”). Namely, a particular organicacid compound is used as the co-existing compound for converting thecrystal form and a non-acidic organic acid compound is used as thecontact compound for converting the crystal form (hereinafter theseparticular organic acid compound and non-acidic organic acid compoundare sometimes collectively referred to as “compound (B) for convertingthe crystal form”)

(C) The crystal form is converted by bringing a phthalocyanine crystalprecursor into contact with an organic compound which is in a liquidstate under conditions of 1013 hPa and 25° C. and does not have afunctional group showing acidity (hereinafter optionally referred to as“non-acidic particular organic compound”) in the presence of an aromaticcompound which is solid under conditions of 1013 hPa and 25° C. and hasan electron-withdrawing substituent (hereinafter optionally referred toas “electron-withdrawing particular aromatic compound”). Namely, anelectron-withdrawing particular aromatic compound is used as theco-existing compound for converting the crystal form and a non-acidicparticular organic compound is used as the contact compound forconverting the crystal form (hereinafter these particular organic acidcompound and non-acidic organic acid compound are sometimes collectivelyreferred to as “compound (C) for converting the crystal form”).

(D) The crystal form is converted by bringing a phthalocyanine crystalprecursor into contact with an aromatic compound having an oxygenatom-containing group and a halogen atom having an atomic weight of 30or more (hereinafter optionally referred to as “particularsubstituent-containing aromatic compound”). Namely, a particularsubstituent-containing aromatic compound is used as the contact compoundfor converting the crystal form (hereinafter the particularsubstituent-containing aromatic compound is sometimes referred to as“compound (D) for converting the crystal form”).

In the crystal form-converting step, among the aforementioned compoundsfor converting the crystal form (A) to (D), any one of the compounds forconverting the crystal form may be used singly or two or more of thecompounds for converting the crystal form may be used in combination atany combination and in any ratio.

In the following, unless otherwise stated, common items will beexplained together regardless of the kind of the compounds forconverting the crystal form and only the items intrinsic to each of thecompounds (A) to (D) for converting the crystal form are explainedindividually.

[Composition of Crystalline Phthalocyanine]

In the invention, the “phthalocyanine crystal” means a crystalcontaining one or two or more phthalocyanine compounds. Namely, not onlya crystal composed of one phthalocyanine compound alone but also a mixedcrystal of a plurality of phthalocyanine compounds or a mixed crystalcomposed of one or two or more phthalocyanine compounds and the othermolecule is called “phthalocyanine crystal” in the invention.

Also, in the invention, the “phthalocyanine compound” means a compoundhaving a phthalocyanine skeleton. Specific examples thereof includemetal-free phthalocyanine; phthalocyanines having a planar molecularstructure, such as cooper phthalocyanine, zinc phthalocyanine, and leadphthalocyanine; phthalocyanines having a shuttlecock structure in themolecule, such as oxytitanium phthalocyanine, oxyvanadiumphthalocyanine, chloroaluminum phthalocyanine, chlorogalliumphthalocyanine, chloroindium phthalocyanine, and hydroxygalliumphthalocyanine; phthalocyanines having a spinning top structure in themolecule, such as dichlorotin phthalocyanine, dichlorosiliconphthalocyanine, dihydroxytin phthalocyanine, and dihydroxysiliconphthalocyanine; and the like.

In the case where the phthalocyanine crystal of the invention iscomposed of a single phthalocyanine, a phthalocyanine having ashuttlecock structure is desirable in view of characteristic propertiesas an electrographic photoreceptor. Moreover, among the phthalocyanineshaving a shuttlecock structure, the central metal of molecule of thephthalocyanine compound is preferably in an oxide, chloride, orhydroxide state since the properties as an electrographic photoreceptoris satisfactory. In view of easiness of the production of thephthalocyanine crystal, the central metal is more preferably in an oxidestate. As specific examples, oxytitanium phthalocyanine or oxyvanadiumphthalocyanine is particularly preferred and oxytitanium phthalocyanineis most preferred.

On the other hand, in the case where the phthalocyanine crystal of theinvention consists of a plurality of molecules, there may be mentioned acase where it is composed of a mixed crystal of a plurality ofphthalocyanine compounds (i.e., it does not contain a compound otherthan a phthalocyanine compound) and a case where it is composed of amixed crystal composed of one or two or more phthalocyanine compoundsand the other molecule (i.e., it contains a compound other than aphthalocyanine compound). In view of crystal stability, the case whereit is composed of a mixed crystal of a plurality of phthalocyaninecompounds (i.e., it does not contain a compound other than aphthalocyanine compound) is preferred.

In the case where the phthalocyanine crystal of the invention is a mixedcrystal, it preferably contains phthalocyanine(s) having a shuttlecockstructure as a main component in view of the properties as anelectrographic photoreceptor. In the phthalocyanine compound to becontained as the main component (hereinafter optionally referred to as“main component phthalocyanine compound”), the central metal of themolecule is preferably in an oxide, chloride, or hydroxide state. Inview of easiness of the production of phthalocyanine crystal, thecentral metal is more preferably in an oxide state. As specificexamples, oxytitanium phthalocyanine or oxyvanadium phthalocyanine isparticularly preferred and oxytitanium phthalocyanine is most preferred.The content of the main component phthalocyanine compound is usually 60%by weight or more relative to the phthalocyanine crystal as a mixedcrystal. Since the crystal form-regulating ability decreases when thecontent is low, the content is preferably 70% by weight or more. Thecontent is more preferably 80% by weight or more in view of crystalstability during dispersing and is further preferably 85% by weight ormore in view of the properties when the phthalocyanine crystal is usedas an electrographic photoreceptor.

Moreover, in the case where the phthalocyanine crystal of the inventionis a mixed crystal, the phthalocyanine compound contained as thephthalocyanine compound other than the aforementioned main-componentphthalocyanine compound (hereinafter optionally referred to as“phthalocyanine compound other than the main component”) is preferably aphthalocyanine compound having a shuttlecock structure or aphthalocyanine compound having a planar molecular structure in view ofcrystal stability. In particular, in view of the properties of theelectrographic photoreceptor, oxyvanadium phthalocyanine, chlorogalliumphthalocyanine, hydroxygallium phthalocyanine, and chloroindiumphthalocyanine are preferred among the phthalocyanine compounds having ashuttlecock structure, and metal-free phthalocyanine, zincphthalocyanine, and lead phthalocyanine are preferred among thephthalocyanines having a planar molecular structure. Among them,oxyvanadium phthalocyanine, chlorogallium phthalocyanine, chloroindiumphthalocyanine, hydroxygallium phthalocyanine, and metal-freephthalocyanine are more preferred. Since vacant space in the mixedcrystal further increases, a metal-free phthalocyanine having a planarmolecular structure is particularly preferred. The phthalocyaninecompound other than the main component may be used singly or two or morethereof may be used in combination at any combination and in any ratiobut the use of only one compound is preferred. The content of thephthalocyanine compound other than the main component is usually 40% byweight or less relative to the phthalocyanine crystal as a mixedcrystal. Since the crystal form-regulating ability decreases when thecontent is too high, the content is preferably 30% by weight or less.The content is preferably 20% by weight or less in view of crystalstability during dispersing and is further preferably 15% by weight orless in view of the electrographic properties. However, when the contentof the phthalocyanine compound other than the main component is too low,the effect of the compound is sometimes not obtained, so that thecontent is preferably 0.1% by weight or more, more preferably 0.5% byweight or more.

[Crystalline Phthalocyanine Precursor]

The phthalocyanine crystal of the invention is obtained through the stepof bringing a phthalocyanine crystal precursor into contact with acompound for converting the crystal form to convert the crystal form.The “phthalocyanine crystal precursor” means a substance which affordsthe phthalocyanine crystal by subjecting the substance to a treatment ofconverting the crystal form (hereinafter sometimes referred to as“crystal form-converting treatment”). Therefore, the phthalocyaninecrystal precursor may be any of one phthalocyanine compound, a mixtureof two or more phthalocyanine compounds, and a mixture of one or two ormore phthalocyanine compounds and one or two or more other compounds (inthe following, a phthalocyanine compound or a mixture containingphthalocyanine compound(s) is sometimes collectively referred to as“phthalocyanine”). Moreover, the existing sate is not particularlylimited but, in view of the crystal form-regulating ability at thecrystal conversion, as the phthalocyanine crystal precursor, anamorphous phthalocyanine or a low-crystalline phthalocyanine having thesame molecular structure as the phthalocyanine crystal to be obtained isused.

In the invention, the “low-crystalline phthalocyanine” means aphthalocyanine which does not have peaks having a half bandwidth of0.30° or less within the range of 0° to 40° in terms of Bragg angle(2θ±0.2°) toward CuKα characteristic X-ray (wavelength 1.541 angstrom)in a powder X-ray diffraction (hereinafter sometimes abbreviated as“XRD”) spectrum. When the half bandwidth is too small, thephthalocyanine molecule is in a state having a certain degree ofconstant regularity and long-term order in the solid, and the crystalform-regulating ability decreases at the conversion of the crystal form,so that the low-crystalline phthalocyanine to be used as thephthalocyanine crystal precursor in the invention is preferably onewhich does not have any peaks having a half bandwidth of usually 0.35°or less, further 0.40° or less, particularly 0.45° or less.

In the present Description, measurement of the powder X-ray diffractionspectrum of phthalocyanines, determination of Bragg angle (2θ±0.2°)toward CuKα characteristic X-ray (wavelength 1.541 angstrom), andcalculation of the peak half bandwidth are carried out under thefollowing conditions.

As a measuring apparatus for the powder X-ray diffraction spectrum, apowder X-ray diffractometer of a converging optical system using a CuKα(CuKα₁+CuKα₂) ray as an X-ray source (e.g., PW1700 manufactured byPANalytical Co.) is employed.

The conditions for measuring the powder X-ray diffraction are a scanningrange (2θ) of 3.0 to 40.0°, a scanning step width of 0.05°, a scanningspeed of 3.0°/min, a divergence slit of 1°, a scattering slit of 1°, anda receiving slit of 0.2 mm.

The peak half bandwidth can be calculated by the profile fitting method.The profile fitting can be performed using a powder X-ray diffractionpattern-analyzing software JADE5.0+ manufactured by MDI. The calculationconditions are as follows. Namely, background is fixed to an idealposition within the whole measurement range (2θ=3.0 to 40.0°). As thefitting function, a Peason-VII function considering contribution ofCuKα₂ is used. As variations of the fitting function, three variations,i.e., a diffraction angle (2θ), a peak height, and a peak half bandwidth(β₀) are precisely determined. With eliminating the influence of CuKα₂,the diffraction angle (2θ), peak height, and peak half bandwidth (β₀)derived from CuKα₁ are calculated. Asymmetry is fixed to 0 and a figureconstant to 1.5.

A peak half bandwidth (β) derived from a sample is determined bycorrecting the peak half bandwidth (β₀) calculated by the above profilefitting using a peak half bandwidth (β_(Si)) of 111 peak (2θ=28.442°) ofstandard Si (NIST Si 640b) calculated under the same measurementconditions and the same profile fitting conditions, according to thefollowing equation.β=√{square root over (β_(o) ²−β_(Si) ²)}[Num 1]

In this connection, although the boundary of the low-crystallinephthalocyanines and the amorphous phthalocyanines is not clear, it ispossible to use any of them as a preferable phthalocyanine crystalprecursor. In the following, the low-crystalline phthalocyanines and theamorphous phthalocyanines are collectively referred to as“low-crystalline/amorphous phthalocyanines” in the case where they arereferred to without particular distinction.

As mentioned below, a crystal form (particular crystal form) having amain diffraction peak at Bragg angle (2θ±0.2°) of 27.2° toward CuK_(α)characteristic X-ray (wavelength 1.541 angstrom) is preferred. Thelow-crystalline phthalocyanine having a peak at around 27.2° ispreferred as the phthalocyanine crystal precursor since the former hasregularity similar to the phthalocyanine crystal having the particularcrystal form and is excellent in crystal form-regulating ability intothe above particular crystal form. The low-crystalline phthalocyanine onthis occasion does not contain peaks having a half bandwidth rangingusually 0.30° or less, preferably 0.35° or less, more preferably 0.40°or less, further preferably 0.45° or less.

On the other hand, in the case where the low-crystalline/amorphousphthalocyanine having no peaks at around 27.2° is used as aphthalocyanine crystal precursor, the crystallinity is desirably lowsince the crystal form-regulating ability into the phthalocyaninecrystal having the above particular crystal form is poor. Thelow-crystalline phthalocyanine on this occasion does not contain peakshaving a half bandwidth ranging usually 0.30° or less, preferably 0.50°or less, more preferably 0.70° or less, further preferably 0.90° orless.

FIGS. 2 to 5 show examples of powder X-ray diffraction spectra of thelow-crystalline/amorphous phthalocyanines. In this connection, theseX-ray diffraction spectra are exemplified in order to explain theinvention in detail. Unless they contradict the gist of the invention,the phthalocyanines usable as the phthalocyanine crystal precursors inthe invention are not limited to the low-crystalline/amorphousphthalocyanines having these X-ray diffraction spectra.

Phthalocyanines having crystallinity (phthalocyanine crystals) are in astate where phthalocyanine molecules have certain regularity andlong-term order in solid and have a clear peak when powder X-raydiffraction spectra are measured. Contrarily, thelow-crystalline/amorphous phthalocyanines are in a state that regularityof the molecular alignment and long-term order of the molecularalignment are decreased and show a harrow figure or, even when they havepeaks, the half bandwidth is very broadened as the powder X-raydiffraction spectra exemplified in FIGS. 2 to 5.

In the invention, as processes for preparing thelow-crystalline/amorphous phthalocyanines to be phthalocyanine crystalprecursors, it is possible to use known processes for preparation, forexample, chemical treatment processes such as acid paste process andacid slurry process, mechanical treatment processes such aspulverization and grinding but the chemical treatment processes arepreferred since more homogeneous low-crystalline/amorphousphthalocyanines are obtained. Of these, the acid paste process is morepreferred.

[Compound for Converting Crystal Form]

[Aromatic Aldehyde Compound]

The compound (A) for converting the crystal form is an aromatic aldehydecompound. The aromatic aldehyde compound is used as the contact compoundfor converting the crystal form.

The aromatic aldehyde compound to be used for obtaining thephthalocyanine crystal of the invention is a compound having an aldehydegroup that is directly bonded to an aromatic ring.

In the aromatic aldehyde compound to be used in the invention, thenumber of the aromatic rings is not particularly limited so long as itis a compound having one or more aromatic rings which satisfy theHückel's rule but the value of n is usually 5 or less in the formula4n+2 (n is an integer) in the Hückel's rule. Of these, in considerationof operability at the crystal conversion and properties of thephotoreceptor of phthalocyanine crystal, the value of n is preferably 3or less, more preferably 2 or less, and further preferably 1.

The kind of the aromatic rings includes aromatic hydrocarbon ringsconsisting of carbon atoms and hydrogen atoms and aromatic heterocycleswherein heteroatom(s) such as nitrogen atom(s), sulfur atom(s), and/oroxygen atom(s) are incorporated into the aromatic ring.

Specific examples of the aromatic ring include known aromatichydrocarbon ring structures and aromatic heterocyclic structures, forexample, anthracene, phenanthrene, acridine, phenanthridine,phenanthroline, phenazine, and the like in the case where n is 3;naphthalene, azulene, quinoline, isoquinoline, quinoxaline,naphthylidine, and the like in the case where n is 2; benzene, pyridine,pyrazine, pyrrole, thiophene, furan, thiazole, oxazole, imidazole, andthe like in the case where n is 1. The above aromatic hydrocarbon ringstructures and aromatic heterocyclic structures may have a condensedring having no aromaticity.

Moreover, the number of the aldehyde groups per molecule contained inthe aromatic aldehyde compound to be used in the invention is notparticularly limited but is usually 1 or more and usually 4 or less,preferably 2 or less.

As a substituent that the aromatic aldehyde compound to be used in theinvention may have other than the aldehyde group, there may be possiblea known substituent, e.g., an alkyl group such as a methyl group, anethyl group, an isopropyl group, or a cyclohexyl group; an alkoxy groupsuch as a methoxy group, an ethoxy group, or a propyloxy group; anaralkyloxy groups such as benzyloxy group; an aryloxy groups such as aphenoxy group; a thioalkyl group such as a thiomethyl group or athioethyl group; an aryl group such as a phenyl group or a naphthylgroup; a nitro group; a cyano group; a carboxy group; a sulfo group; asulfino group; a sulfeno group; a hydroxy group; a mercapto group; ahalogen atom such as a chlorine atom, a bromine atom, and a fluorineatom; a ketone group such as an acetyl group; an amido group such ascarboxamido group; a substituted or unsubstituted amino group such anamino group, a monomethylamino group, or a methylethylamino group; anester group such as a methyloxycarbonyl group or an ethyloxycarbonylgroup; a halogenated alkyl group such as a trifluoromethyl group; andthe like.

Among the above examples of the substituent, the substituents having acarbon chain in the substituent, such as an alkyl group, an alkoxygroup, a substituted amino group, an ester group, and a ketone group mayhave any of linear, branched, and cyclic structures in the carbon chainportion but a linear or branched structure is preferred since too largestructure of the carbon chain part of these substituents may adverselyinfluence crystal stability. Moreover, the number of carbon atoms of thecarbon chain portion in these substituents is usually 20 or less. Whenthe number of carbon atoms of the carbon chain portion is too large, theeffect of the aromatic aldehyde compound decreases, so that the numberof the carbon atoms is preferably 15 or less, more preferably 10 orless.

Among the above substituents, from the viewpoint of the crystalform-regulating ability and charge-generating ability, preferred are ahalogen atom, an alkyl group, an alkoxy group, a ketone group, an estergroup, a carboxyl group, a nitro group, and the like and more preferredare a halogen atom, a ketone group, and an alkoxy group.

The number of the substituents that the aromatic aldehyde compound to beused in the invention has other than the aldehyde group is notparticularly limited. However, in consideration of the operability inthe crystal conversion and the properties of photographic photoreceptorof the phthalocyanine crystal, the number thereof is preferably 5 orless, more preferably 3 or less, further preferably 1 or less. In thisconnection, the substituents other than the aldehyde group may becombined together to form a ring structure.

Examples of the aromatic aldehyde compound include those having anaromatic hydrocarbon ring and those having an aromatic heterocyclicring.

Specific examples of the aromatic aldehyde compound having an aromatichydrocarbon ring include benzaldehydes such as fluorobenzaldehyde,chlorobenzaldehyde, methoxybenzaldehyde, nitorbenzaldehyde,phenylbenzaldehyde, and 1,2,3,4-tetrahydronaphthaldehyde;naphthaldehydes such as 1-naphthaldehyde and 2-naphthaldehyde, andanthaldehydes such as 9-anthaldehyde.

Specific examples of the aromatic aldehyde compound having an aromaticheterocyclic ring include pyridinecarbaldehydes such as2-pyridinecarbaldehyde; quinolinecarbaldehydes such as2-quinolinecarbaldehyde; thiophenealdehydes such as 2-thiophenealdehyde;and pyrrolecarbaldehydes such as pyrrole-2-carbaldehyde.

Among the above aromatic aldehyde compounds, in view of thecrystal-converting ability, preferred are aromatic aldehyde compoundswherein the aldehyde group is directly bonded to the aromatichydrocarbon ring and, in particular, more preferred are benzaldehydes inview of stability for environmental fluctuation when used in theelectrophotographic photoreceptor.

In this connection, the above aromatic aldehyde compounds may be usedsingly or two or more thereof may be used in combination at anycombination and in any ratio.

Moreover, one or more aromatic aldehyde compounds may be mixed with oneor more other compounds and the mixture may be brought into contact withthe phthalocyanine crystal precursor. In this case, the kind of theother compound to be used in combination with the aromatic aldehydecompound is not particularly limited unless it adversely influences thephthalocyanine crystal precursor used and the phthalocyanine crystal tobe obtained. However, in the case where the other compound other thanthe aromatic aldehyde compound is used in combination, it is preferredthat the ratio of the aromatic aldehyde compound to the total amount ofthe aromatic aldehyde compound and the other compound is usually 50% byweight or more, particularly 75% by weight or more.

The amount of the aromatic aldehyde compound to be used varies dependingon the procedure to be used for contact treatment and cannot becategorically defined. However, in general, the amount ranges usually50% by weight or more, preferably 100% by weight or more and usually2000% by weight or less, preferably 1000% by weight or less in terms ofthe weight ratio to the phthalocyanine crystal precursor. In thisconnection, in the case where two or more aromatic aldehyde compoundsare used in combination, the ratio of the total thereof may satisfy theabove range.

[Particular Organic Acid Compound]

The compound (B) for converting the crystal form consists of at leastone compound selected from the group consisting of organic acids,organic acid anhydrides, and organic acid esters having a heteroatom andan organic compound having no acidic functional group (non-acidicorganic compound). The particular organic acid compound is used as aco-existing compound for converting the crystal form and the non-acidicorganic compound is used as the contact compound for converting thecrystal form.

The phthalocyanine crystal of the invention is obtained by bringing theabove phthalocyanine crystal precursor into contact with a non-acidicorganic compound to be mentioned below in the presence of at least onecompound selected from the group consisting of organic acids, organicacid anhydrides, and organic acid esters having a heteroatom(hereinafter, optionally abbreviated as “particular organic acidcompound”) to convert the crystal form.

<Organic Acid>

The organic acid is a generic term of the compounds showing acidity.Specifically, it is a compound having a functional group showing acidity(hereinafter optionally abbreviated as “acidic functional group”), suchas a carboxylic acid, a sulfonic acid, a sulfinic acid, a sulfenic acid,a phenol, an enol, a thiol, a phosphonic acid, a phosphoric acid, aboric acid, an imidic acid, a hydrazonic acid, a hydroxymic acid, or ahydroxamic acid.

The organic acid to be used in the invention is not particularly limitedso long as it is a compound having any of the aforementioned variousacidic functional groups but, in view of the versatility and stabilityof the reagent, an organic acid having an acidic functional groupcomposed of a carbon atom, an oxygen atom, a sulfur atom, a phosphorusatom, and/or a boron atom is usually used. Examples of such an organicacid include a carboxylic acid, a sulfonic acid, a sulfinic acid, aphenol, a thiol, a phosphonic acid, phosphoric acid, boronic acid, boricacid, and the like. Of these, in consideration of the properties of theelectrophotographic photoreceptor to be obtained using the resultingphthalocyanine crystal as a material, preferred are a carboxylic acid, asulfonic acid, a phenol, a phosphonic acid, phosphoric acid, and boronicacid and more preferred are a carboxylic acid, a sulfonic acid, aphosphonic acid, phosphoric acid, and boronic acid.

The acidic functional group may have any known structure and examplesthereof include a carboxyl group, a thiocarboxyl group, a dithiocarboxylgroup, a mercaptocarbonyl group, a hydroperoxy group, a sulfo group, asulfino group, a sulfeno group, a phenolic hydroxyl group, a thiolgroup, a phosphinico group, a phosphono group, a seleneno group, aselenino group, an arsinico group, an arsono group, a boronic acidgroup, a boranic acid group, and the like. Among these acidic functionalgroups, in view of the versatility and stability of the startingmaterial, an acidic functional group composed of a carbon atom, anoxygen atom, a sulfur atom, a phosphorus atom, and/or a boron atom isusually preferred. More preferred are a carboxyl group, a thiocarboxylgroup, a sulfo group, a sulfino group, a sulfeno group, a phenolichydroxyl group, a thiol group, a phosphinico group, a phosphono group, aboronic acid group, and a boranic acid group and, in view of theproperties as an electrophotographic photoreceptor, further preferredare a carboxyl group, a phosphinico group, a phosphono group, a sulfogroup, and a boronic acid group.

The organic acid to be used in the invention exhibits the advantages ofthe invention through the existence of the acidic functional group inthe structure. Therefore, one molecule of the organic acid contains atleast one acidic functional group but may contain a plurality of thegroups. In the case where a plurality of the acidic functional groupsare contained in one molecule of the organic acid, these acidicfunctional groups may be the same or different from each other. However,when the number of the acidic functional group per one molecule of theorganic acid is too large, the solubility toward the non-acidic organiccompound to be used in combination decreases, so that the number ispreferably 10 or less, more preferably 7 or less, further preferably 4or less.

The organic acid can be distinguished into an acidic functional groupportion and a portion other than the acidic functional group portion (anorganic residue portion) from the viewpoint of the structure. Thestructure of the acidic functional group portion is as mentioned abovebut the structure of the organic residue portion is not particularlylimited and may have any known structure. However, the molecule of thephthalocyanine compound (hereinafter sometimes abbreviated as“phthalocyanine molecule”) has a large number of π electrons in thestructure and the phthalocyanine crystal is constructed by thephthalocyanine molecules through developed interaction of the πelectrons, so that the incorporation of the organic acid into thephthalocyanine crystal is facilitated as the interaction between thephthalocyanine molecule and the organic acid increases. Therefore, inorder to increase the interaction between the organic acid and thephthalocyanine molecule, the organic residue portion of the organic acidhas preferably a structure having π electrons. The number of the πelectrons contained in the organic residue portion is not particularlylimited and it is sufficient to contain at least two π electrons per onemolecule of the organic acid (i.e., at least one carbon-carbon doublebond). However, from the viewpoint of increasing the interaction withthe phthalocyanine molecule, the organic residue portion preferablycontains a structure having an aromaticity that satisfies the Hückel'srule.

The molecular weight of the organic acid to be used in the invention isnot particularly limited but ranges usually 50 or more, preferably 100or more and usually 1200 or less, preferably 1000 or less. When themolecular weight of the organic acid is too small, the solubility inwater increases and thereby the amount thereof in the phthalocyaninecrystal decreases, so that the advantages of the invention tend tolower. Moreover, when the molecular weight of the organic acid is toolarge, the molecular volume of the organic acid becomes too large, sothat the amount thereof in the phthalocyanine crystal decreases andhence the advantages of the invention tends to lower. In particular,when the molecular volume of organic residue portion of the organic acidis too large, the incorporation into the phthalocyanine crystal becomesdifficult, so that the molecular weight of the organic residue portionis usually 1000 or less, preferably 500 or less, more preferably 400 orless, further preferably 300 or less.

As the state of the organic acid, there may be a state of the organicacid as it is, a state where the organic acid is ionized, a state wherean ion of the organic acid is bonded to a counter ion to form a salt, orthe like. However, in the invention, since it is presumed that theorganic residue portion contributes the exhibition of the advantagesthrough the incorporation of the organic acid itself into the crystal,the organic acid to be used in the invention may be any of theaforementioned states.

As mentioned below, in the invention, the co-existence of water ispreferred at the contact of the phthalocyanine crystal precursor withthe non-acidic organic compound in the presence of the particularorganic acid compound. Therefore, it is possible to use, as theparticular organic acid compound, a compound which is a compound otherthan the organic acid at a stage before the contact treatment but isconverted into the organic acid by the contact with water throughhydrolysis or the like. In the following, such a compound is alsocollectively referred to as “organic acid”.

<Organic Acid Anhydride>

The organic acid anhydride is a compound having a bond wherein two acylgroups share one oxygen atom (hereinafter optionally referred to as“acid anhydride bond”). As main organic acid anhydrides, there may bementioned those wherein two molecules of an organic acid having oneacidic functional group form an acid anhydride bond between themolecules and those wherein an organic acid having two or more acidicfunctional groups forms an acid anhydride bond in a single molecule. Theformer is further classified into those wherein two molecules of thesame kind of an organic acid form an acid anhydride bond and thosewherein two molecules of different kinds of organic acids form an acidanhydride bond. The kind of the organic acid anhydride to be used in theinvention is not particularly limited and it may be any of these organicacid anhydrides.

Examples of the organic acid anhydride include carboxylic acidanhydrides wherein two molecules of the same kind of a carboxylic acidform an acid anhydride bond between the molecules, such as aceticanhydride, propionic anhydride, butyric anhydride, and trifluoroaceticanhydride; carboxylic acid anhydrides wherein two molecules of differentkinds of dicarboxylic acids form an acid anhydride bond between themolecules, such as acetic propionic anhydride and acetic trifluoroaceticanhydride; carboxylic anhydrides wherein a dicarboxylic acid forms anacid anhydride bond in the same molecule, such as phthalic anhydride,maleic anhydride, succinic anhydride, 1,2-naphthoic anhydride, and1,8-naphthoic anhydride; sulfonic anhydride wherein two molecules of thesame or different kind of sulfonic acid(s) form an acid anhydride bondbetween the molecules, such as benzenesulfonic anhydride; sulfinicanhydride wherein two molecules of the same or different kind ofsulfinic acid(s) form an acid anhydride bond between the molecules, suchas benzenesulfinic anhydride; linear or cyclic organic acid anhydridewherein two molecules of the same or different kind of organic acid(s)form an acid anhydride bond between the molecules, such asbenzensulfonic benzenesulfinic anhydride and cyclic sulfoaceticanhydride; and the like. Of these, as the organic acid anhydride to beused in the invention, from the viewpoint of the properties as theelectrophotographic photoreceptor, preferred are carboxylic anhydridescomposed of the same acids, carboxylic anhydrides composed of differentacids, carboxylic anhydrides having an acid anhydride bond within amolecule, and sulfonic acid anhydrides, and more preferred arecarboxylic anhydrides composed of the same acids and carboxylicanhydrides having an acid anhydride bond within a molecule.

In this connection, the structure of the portion other than the acidanhydride bond of the organic acid anhydride to be used (organic residueportion) in the invention is not particularly limited and may be anystructure but is preferably a structure having π electrons for thereasons illustrated in the article of the above <Organic Acid>. Thenumber of the π electrons contained in the organic residue portion isnot particularly limited and it is sufficient to contain at least two πelectrons per one molecule of the organic acid (i.e., at least onecarbon-carbon double bond). However, form the viewpoint of increasingthe interaction with the phthalocyanine molecule, the organic residueportion preferably contains a structure having aromaticity thatsatisfies the Hückel's rule.

The molecular weight of the organic acid anhydride is not particularlylimited but is usually 1000 or less, preferably 500 or less, morepreferably 400 or less, further preferably 300 or less since theanhydride tends to be hardly incorporated into phthalocyanine crystalwhen the anhydride is too large. On the other hand, when the molecularweight of the organic acid is too small, the interaction with thephthalocyanine molecule decreases and the amount thereof in thephthalocyanine crystal is reduced, so that the advantages of theinvention tends to lower. Thus, a lower limit of the molecular weight isusually 50 or more, preferably 100 or more.

<Organic Acid Ester Having Heteroatom>

The organic acid ester having a heteroatom is an organic compoundwherein the acidic functional group portion of the organic acid having aheteroatom is changed into an organic acid ester showing no acidity. Asan example, there may be mentioned a compound showing no acidity whereina sulfonic group having acidity is changed into a methyl sulfonategroup.

The heteroatom generally means an atom other than a carbon atom and ahydrogen atom among the atoms constituting an organic compound. However,an organic acid usually contains at least oxygen and/or nitrogen atomsin the acidic functional group. Therefore, when oxygen and nitrogenatoms are included in the heteroatom, all the organic acid esters areincluded in the organic acid esters having a heteroatom and thus thedefinition is not appropriate. Accordingly, in the invention, atomsother than carbon, hydrogen, nitrogen, and oxygen atoms are defined asheteroatoms.

In general, as heteroatoms to be introduced into the structures oforganic compounds, there may be mentioned boron, sulfur, phosphorus,silicon, selenium, tellurium atoms, and the like. However, asheteroatoms contained in the organic acid esters to be used in theinvention, boron, sulfur, and phosphorus atoms are usually used. Ofthese, sulfur and phosphorus atoms are preferred in consideration ofversatility of the organic acid esters to be used in the invention.

In the structure of the organic acid ester to be used in the invention,the site to which the heteroatom is introduced is not particularlylimited and may be introduced into any site but the heteroatom ispreferably contained in the acidic functional group portion (e.g., sulfoor phosphono groups, etc.) in the structure of the organic acid beforeit is derivatized into the organic acid ester. Namely, the organic acidester to be used in the invention preferably has an acid ester groupcontaining a heteroatom.

In the structure of the organic acid ester group containing a heteroatomto be used in the invention, the structure of the portion other than theacid ester group containing a heteroatom (organic residue portion) isnot particularly limited and may be any structure but a structure havingπ electrons is preferred for the reasons illustrated in the article ofthe above <Organic Acid>. The number of the π electrons contained in theorganic residue portion is not particularly limited and it is sufficientto contain at least two π electrons per one molecule of the organic acidester (i.e., at least one carbon-carbon double bond). However, from theviewpoint of increasing the interaction with the phthalocyaninemolecule, the organic residue portion preferably contains a structurehaving aromaticity that satisfies the Hückel's rule.

Examples of the organic acid ester containing a heteroatom includephosphonic acid esters such as dimethyl methylphosphonate, dimethylphenylphosphonate, and diethyl pheylphosphonate; phosphoric acid esterssuch as dimethyl methyl phosphate and dimethyl phenyl phosphate;sulfonic acid esters such as methyl methanesulfonate, methylbenzenesulfonate, and ethyl benzenesulfonate; sulfinic acid esters suchas methyl methylsulfinate and methyl phenylsulfinate; sulfinoic acidesters such as methyl methylsulfinoate and methyl phenylsulfinoate;boronic acid esters such as dimethyl methylboronate and dimethylpenylboronate; and the like. Of these, in view of versatility of thereagent, preferred are phosphonic acid esters, phosphoric acid esters,sulfonic acid esters, and boronic acid esters and more preferred arephosphonic acid esters and sulfonic acid esters.

The molecular weight of the organic acid ester containing a heteroatomis not particularly limited but is usually 1000 or less, preferably 500or less, more preferably 400 or less, further preferably 300 or lesssince the ester tends to be hardly incorporated into phthalocyaninecrystal when the ester is too large. On the other hand, when themolecular weight of the organic acid ester containing a heteroatom istoo small, the interaction with the phthalocyanine molecule reduces andthe amount of the organic acid ester containing a heteroatom in thephthalocyanine crystal decreases, so that the advantages of theinvention tends to lower. Thus, a lower limit of the molecular weight isusually 50 or more, preferably 100 or more.

<Others>

As the particular organic acid compound, any compound of theaforementioned organic acids, organic acid anhydrides, and organic acidesters containing a heteroatom is used. Any one particular organic acidcompound may be used singly or two or more particular organic acidcompounds may be used in combination in any combinations and ratio. Inparticular, in the case where two or more particular organic acidcompounds may be used in combination, among three categories, i.e., theorganic acid, the organic acid anhydride, and the organic acid estercontaining a heteroatom, two or more compounds may be selected from anyone categories and used in combination or one or two or more compoundsmay be selected from each of any two or all three categories and used incombination.

Moreover, the existing form of the particular organic acid compound isalso not particularly limited and may be any of liquid, gas, or solid.

[Non-Acidic Organic Compound]

The phthalocyanine crystal of the invention is obtained by bringing theaforementioned phthalocyanine crystal precursor into contact with anorganic compound having no acidic functional group (it is optionallyabbreviated as “non-acidic organic compound”) in the presence of theaforementioned organic acid compound.

The non-acidic organic compound to be used in the invention is referredto an organic compound which does not have an acidic functional groupillustrated in the above article of <Organic Acid> in the structure.With the non-acidic organic compound to be used in the invention, thekind thereof is not particularly limited so long as it has an ability ofconverting the crystal form.

The non-acidic organic compound is roughly classified into an aliphaticcompound and an aromatic compound (in the following, they are optionallyreferred to as “non-acidic aliphatic compound” and “non-acidic aromaticcompound”, respectively).

Examples of the non-acidic aliphatic compound include saturated orunsaturated aliphatic hydrocarbon compounds such as pinene, terpinene,hexane, cyclohexane, octane, decane, 2-methylpentane, ligroin, andpetroleum benzine; aliphatic ether compounds such as diethyl ether,diisopropyl ether, dibutyl ether, dimethyl cellosolve, ethylene glycoldibutyl ether, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane;halogenated aliphatic compounds such as dichloromethane, chloroform,carbon tetrachloride, 1,2-dichloroethane, and 1,2,2,2-tetrachloroethane;aliphatic ketone compounds such as methyl ethyl ketone, methyl isobutylketone, diisopropyl ketone, diisobutyl ketone, cyclohexanone, andcyclopentanone; aliphatic ester compounds such as ethyl acetate, propylacetate, butyl acetate, isobutyl acetate, hexyl acetate, butyl acrylate,methyl propionate, and cyclohexyl acetate; aliphatic alcohol compoundssuch as methanol, ethanol, and butanol; aliphatic aldehyde compoundssuch as n-propylaldehyde and n-butylaldehyde; and the like. In thisconnection, the hydrocarbon skeletons contained in these non-acidicaliphatic compounds may be chain (straight chain or branched chain) orcyclic one or may be those wherein chain and cyclic one are combined.

On the other hand, examples of the non-acidic aromatic compound includearomatic hydrocarbon compounds such as toluene, xylene, naphthalene,biphenyl, and terphenyl; halogenated aromatic hydrocarbon compounds suchas monochlorobenzene, dichlorobenzene, trichlorobenzene,dichlorotoluene, chloronaphthalene, and bromobenzene; aromatic nitrocompounds such as nitrobenznene and fluoronitrobenzene; aromatic estercompounds such as butyl benzoate, methyl chlorobenzoate, methylmethylbenzoate, and phenyl acetate; aromatic ether compounds such asdiphenyl ether, anisole, and chloroanisole; aromatic aldehyde compoundssuch as benzaldehyde and chlorobenzaldehyde; aromatic ketone compoundssuch as acetophenone and chloroacetophenone; heterocyclic aromaticcompounds such as thiophene, furan, quinoline, and picoline; and thelike.

Among these non-acidic organic compounds, in view of the crystalform-converting ability, preferred are aliphatic compounds or aromaticcompounds containing a halogen atom or an oxygen atom or aromatichydrocarbon compounds. Of these, in consideration of stability of theresulting phthalocyanine crystal at dispersing, more preferred arehalogenated aliphatic compounds, aliphatic ether compounds, aliphaticketone compounds, aliphatic ester compounds, aromatic hydrocarboncompounds, halogenated aromatic compounds, aromatic nitro compounds,aromatic ketone compounds, aromatic ester compounds, and aromaticaldehyde compounds. From the viewpoint of the properties of theelectrophotographic photoreceptor using the resulting phthalocyaninecrystal as a material, further preferred are aliphatic ether compounds,halogenated aromatic compounds, aromatic nitro compounds, aromaticketone compounds, aromatic ester compounds, and aromatic aldehydecompounds.

In this connection, these non-acidic organic compounds sometimes belongsimultaneously to a plurality of compound groups of the aforementionedcompound groups depending on the kind of the substituent and the like inthe structure (for example, nitrochlorobenzene belongs to both of the“halogenated aromatic compound” and the “aromatic nitro compound”) butsuch a non-acidic organic compound is judged as one having all theattributes of a plurality of these classifications (for example,nitrochlorobenzene has attributes of both of the halogenated aromaticcompound and the aromatic nitro compound).

Any one of these non-acidic organic compounds may be used singly or twoor more thereof may be used in combination at any combination and in anyratio.

The existing form or the non-acidic organic compound is not particularlylimited and may be any of liquid, gas, or solid but, since the contacttreatment of the non-acidic organic compound with the phthalocyaninecrystal is usually carried out in a state where the non-acidic organiccompound is liquid, the melting point of the non-acidic organic compoundis usually 150° C. or lower, preferably 100° C. or lower, morepreferably 80° C. or lower.

The molecular weight of the non-acidic organic compound is also notparticularly limited but, since the contact treatment of the non-acidicorganic compound with the phthalocyanine crystal is usually carried outin a state where the non-acidic organic compound is liquid, too largemolecular weight of the non-acidic organic compound is not desirable.Specifically, the molecular weight of the non-acidic organic compound isusually 1000 or less, preferably 500 or less, more preferably 400 orless, further preferably 300 or less. On the other hand, when themolecular weight of the non-acidic organic compound is too small, theboiling point thereof is generally lowered and is easily vaporized andthus the handling properties at production tends to be impaired, so thata lower limit of the molecular weight is usually 50 or more, preferably100 or more.

[Combined Use of Particular Organic Acid Compound and Non-Acidic OrganicCompound]

The mechanism why the properties of the electrophotographicphotoreceptor using the resulting phthalocyanine crystal as a materialare improved by combined use of the particular organic acid compound andthe non-acidic organic compound as the compound (B) for converting thecrystal form at the crystal conversion treatment of the phthalocyaninecrystal precursor is not clear. However, it is presumed that theadvantages of the invention is obtained by more efficient incorporationof the particular organic acid compound simultaneously used intophthalocyanine crystal realized by the co-existence of the non-acidicorganic compound at the crystal conversion treatment.

[Electron-Withdrawing Particular Aromatic Compound]

The compound (C) for converting the crystal form is composed of thearomatic compound which is solid under conditions of 1013 hPa and 25° C.and has an electron-withdrawing substituent (hereinafter optionallyreferred to as “electron-withdrawing particular aromatic compound”) andthe organic compound which is in a liquid state under conditions of 1013hPa and 25° C. and does not have a functional group showing acidity(hereinafter optionally referred to as “non-acidic particular organiccompound”). The electron-withdrawing particular aromatic compound isused as the co-existing compound for converting the crystal form and thenon-acidic particular organic compound is used as the contact compoundfor converting the crystal form.

The electron-withdrawing particular aromatic compound is an aromaticcompound which is solid under conditions of 1013 hPa and 25° C. and hasan electron-withdrawing substituent (hereinafter optionally referred toas “electron-withdrawing group”).

The phthalocyanine crystal of the invention is obtained by bringing theaforementioned phthalocyanine crystal precursor into contact with thenon-acidic particular organic compound in the presence of theelectron-withdrawing particular aromatic compound to convert the crystalform.

In the invention, the “electron-withdrawing group” refers to asubstituent wherein the substituent constant σ_(p) ⁰ in the Hammett rule(hereinafter, sometimes simply referred to as “substituent constantσ_(p) ⁰”) shows a positive value. The “Hammett relation rule” is anempirical rule used for explaining the effect of a substituent on theelectron state of an aromatic ring in an aromatic compound. In general,as described in “Kagaku Binran Kiso-hen II revised 4th edition” editedby the Chemical Society of Japan (published by Maruzen on Sep. 30,1993), page 379, the value is calculated as a value obtained bysubtracting pKa of a benzoic acid having the substituent from pKa ofunsubstituted benzoic acid. The value of the substituent constant σ_(p)⁰ becomes a positive value having a large absolute value as theelectron-withdrawing property enhances and the value becomes a negativevalue having a large absolute value as the electron-donating propertyenhances when the value in the case of hydrogen is regarded as zero.Accordingly, by using the substituent constant σ_(p) ⁰, it becomespossible to surmise and express the electron state and electron densityof an aromatic compound having a substituent. For representativesubstituents, the values of substituent constant σ_(p) ⁰ described in“Kagaku Binran Kiso-hen II revised 4th edition” edited by the ChemicalSociety of Japan (published by Maruzen on Sep. 30, 1993) are shown inthe following Table 1. In the invention, for substituent for which thevalues of the substituent constant σ_(p) ⁰ are described in the aboveliterature, the values are used. For substituents not described, thevalues are determined by the measurement under the same conditions asthe measuring conditions of the values of the substituent constant σ_(p)⁰ described in “Kagaku Binran Kiso-hen II revised 4th edition” edited bythe Chemical Society of Japan (published by Maruzen on Sep. 30, 1993),followed by calculation.

TABLE 1 Substituent Substituent constant σ_(p) ⁰ —N(CH₃)₂ −0.43 —OH−0.16 —CH₃ −0.12 —OCH₃ −0.10 —CH═CH₂ −0.01 —H 0.00 —Ph (phenyl group)0.04 —F 0.20 —Cl 0.28 —Br 0.30 —COOCH₃ 0.46 —COCH₃ 0.49 —CHO 0.53 —CF₃0.54 —CN 0.67 —NO₂ 0.81

The kind of the electron-withdrawing group contained in theelectron-withdrawing particular aromatic compound to be used in theinvention is not particularly limited so long as it has a value of thesubstituent constant σ_(p) ⁰ larger than 0. However, in view of thestability of the properties of the resulting electrophotographicphotoreceptor against environmental fluctuation, an electron-withdrawinggroup having a value of the substituent constant σ_(p) ⁰ of usually0.200 or more, particularly 0.300 or more is preferred.

The number of the electron-withdrawing groups contained in theelectron-withdrawing particular aromatic compound to be used in theinvention is not particularly limited so long as it is one or more. Whenthe number of the electron-withdrawing groups is too large, thesolubility to the non-acidic particular organic compound decreases andthe effect obtained is lowered, so that the number is preferably 5 orless, more preferably 4 or less, further preferably 3 or less. In thecase where the electron-withdrawing particular aromatic compound has twoor more electron-withdrawing groups, they may be the same or differentfrom each other.

Specific examples of the electron-withdrawing group contained in theelectron-withdrawing particular aromatic compound to be used in theinvention include a fluorine atom, a chlorine atom, a bromine atom, aniodine atom, a cyano group, an aldehyde group, a nitro group, a nitrosogroup, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group,an aralkyloxycarbonyl group, an alkoxysulfonyl group, an alkoxysulfinylgroup, an alkylsulfonyloxy group, an alkylsulfinyloxy group, afluoroalkyl group, a carboxyamido group, a sulfonamido group, acarboxyimido group, an azo group, an aryl group, a thioalkyl group, acarboxyl group, a sulfo group, a sulfino group, a sulfeno group, aphosphinico group, a phosphono group, a boronic acid group, a boranicacid group, and the like. Of these, in view of versatility and stabilityof the electron-withdrawing particular aromatic compound, a fluorineatom, a chlorine atom, a cyano group, an aldehyde group, a nitro group,an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, anaralkyloxycarbonyl group, a fluoroalkyl group, a carboxyl group, a sulfogroup, and boronic acid group are preferred. More preferred are a cyanogroup, a nitro group, an acyl group, an alkoxycarbonyl group, anaryloxycarbonyl group, an aralkyloxycarbonyl group, a carboxyl group,and boronic acid group, and further preferred are a cyano group, a nitrogroup, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group,an aralkyloxycarbonyl group, and a carboxyl group.

When the molecular weight of the electron-withdrawing group contained inthe electron-withdrawing particular aromatic compound to be used in theinvention is too large, the molecular volume of the whole compoundincreases and the compound tends to be hardly incorporated into thephthalocyanine crystal, so that the molecular weight is usually 300 orless, preferably 250 or less, more preferably 200 or less, furtherpreferably 150 or less.

The electron-withdrawing particular aromatic compound to be used in theinvention can be separated into an electron-withdrawing group portionand a portion other than the electron-withdrawing group (aromatic ringportion) from the viewpoint of its structure.

The structure of the aromatic ring portion of the electron-withdrawingparticular aromatic compound to be used in the invention may be anystructure so long as it is a structure having π electrons having numberof 4n+2 (where n is an integer of 0 or more) in a planar cyclic polyene,i.e., a structure having aromaticity that satisfies the Hückel's rule.When the structure of the aromatic ring portion is too large, manyadverse effects such as decrease in solubility may sometimes result in,so that n is preferably 5 or less, more preferably 4 or less, furtherpreferably 3 or less in the Hückel's rule.

Examples of the aromatic ring portion of the electron-withdrawingparticular aromatic compound to be used in the invention includearomatic rings consisting of hydrocarbon(s) such as benzene,naphthalene, azulene, anthracene, phenanthrene, fluorene, pyrene, andperylene; aromatic rings containing heteroatom(s), such as pyrrole,thiophene, furan, silole, pyridine, indole, chroman, benzothiophene,benzofuran, quinoline, isoquinoline, carbazole, acridine, phenoxazine,and thianthrene; and the like. Of these aromatic rings, form theviewpoint of the solubility to the non-acidic particular organiccompounds, an aromatic ring wherein the number of elements constitutingthe aromatic ring is 14 or less is preferred and an aromatic ringwherein the number of elements is 10 or less is more preferred.Moreover, an aromatic ring composed of a hydrocarbon is more preferredand benzene and naphthalene are further preferred.

When the molecular weight of the aromatic ring portion of theelectron-withdrawing particular aromatic compound to be used in theinvention is too large, the electron-withdrawing particular aromaticcompound tends to be hardly incorporated into the phthalocyaninecrystal, so that the molecular weight is usually 1000 or less,preferably 500 or less, more preferably 300 or less, further preferably200 or less.

The electron-withdrawing particular aromatic compound to be used in theinvention may have a substituent other than the aforementionedelectron-withdrawing group. Examples of the substituent which theelectron-withdrawing particular aromatic compound may contain other thanthe electron-withdrawing groups include an alkyl group, an aralkylgroup, an alkoxy group, an aryloxy group, an aralkyloxy group, analkenyl group, a phenolic hydroxyl group, a substituted or unsubstitutedamino group, and the like. Since the advantages of the invention arehardly obtained when the electron-donating property increases, an alkylgroup and an alkenyl group are preferred and an alkyl group is morepreferred. When the molecular weight is too large, the molecular volumeof the whole electron-withdrawing particular aromatic compound becomeslarge and thus the compound is hardly incorporated into thephthalocyanine crystal as in the case of the electron-withdrawing group,so that the molecular weight is usually 300 or less, preferably 250 orless, more preferably 200 or less, further preferably 150 or less.

Moreover, the electron-withdrawing particular aromatic compound to beused in the invention is solid under conditions of 1013 hPa (760 mmHg)and 25° C. The compound satisfying such a requirement is preferred forthe reason that it has a strong interaction with a phthalocyaninemolecule.

Examples of the structure of the electron-withdrawing particulararomatic compound to be suitably used in the invention are mentionedbelow. However, the following structures are simply illustrated asexamples and the structures of the electron-withdrawing particulararomatic compound usable in the invention are not limited to thefollowing examples. Electron-withdrawing particular aromatic compoundshaving any structure can be used unless they contradict the gist of theinvention. In the following structural formulae, “Me” represents amethyl group, “Ph” represents a phenyl group, and “Bz” represents abenzoyl group.

In this connection, as the electron-withdrawing particular aromaticcompound, any one may be used singly or two or more may be used incombination at any combination and in any ratio.

[Non-Acidic Particular Organic Compound]

The non-acidic particular organic compound is referred to an organiccompound which is in a liquid state under conditions of 1013 hPa and 25°C. and does not have a functional group showing acidity. Namely, amongthe non-acidic organic compounds explained in the article of thecompound (B) for converting the crystal form, the compound which is in aliquid state under conditions of 1013 hPa and 25° C. corresponds to thenon-acidic particular organic compound.

In the invention, the “functional group showing acidity” is a functionalgroup contained in the structure of an organic acid, which functions forshowing acidity. Examples include a carboxyl group, a thicarboxyl group,a dithiocarboxyl group, a mercaptocarbonyl group, a hydroperoxy group, asulfo group, a sulfino group, a sulfino group, a sulfeno acid group, aphenolic hydroxy group, a thiol group, a phosphinico group, a phosphonogroup, a seleneno group, a selenino group, an arsinico group, an arsonogroup, a boronic acid group, a boranic acid group, and the like asexplained in the article of the above “Organic Acid”. The non-acidicparticular organic compounds to be used in the invention are organiccompounds which do not have any functional group showing the aciditythereof.

The non-acidic particular organic compound to be used in the inventionmay have any structure but the compound is preferably an organiccompound having no unsubstituted amino group, monosubstituted aminogroup, and alcoholic hydroxyl group form the viewpoint of regulating thecrystal form at the contact with the phthalocyanine crystal precursor.

The non-acidic particular organic compound to be used in the inventionis roughly classified into an aliphatic compound and an aromaticcompound (hereinafter, they are optionally referred to as a “non-acidicparticular aliphatic compound” and a “non-acidic particular aromaticcompound”, respectively).

Examples of the non-acidic particular aliphatic compound includesaturated or unsaturated aliphatic hydrocarbon compounds such as pinene,terpinene, hexane, cyclohexane, octane, decane, 2-methylpentane,ligroin, petroleum benzin; aliphatic ether compounds such as diethylether, diisopropyl ether, dibutyl ether, dimethyl cellosolve, ethyleneglycol dibutyl ether, tetrahydrofuran, 1,4-dioxane, and 1,3-dioxolane;halogenated aliphatic compounds such as dichloromethane, chloroform,carbon tetrachloride, 1,2-dichloroethane, and 1,2,2,2-tetrachloroethane;aliphatic ketone compounds such as methyl ethyl ketone, methyl isobutylketone, diisopropyl ketone, diisobutyl ketone, cyclohexanone, andcyclopentanone; aliphatic ester compounds such as ethyl acetate, propylacetate, butyl acetate, isobutyl acetate, hexyl acetate, butyl acrylate,methyl propionate, cyclohexyl acetate; aliphatic alcohol compounds suchas methanol, ethanolm and butanol; aliphatic aldehyde compounds such asn-propylaldehyde and n-butylaldehyde; and the like. In this connection,the hydrocarbon skeleton contained in the non-acidic particularaliphatic compound may be chain (linear chain or branched chain) orcyclic one or may be those wherein chain and cyclic one are combined.

On the other hand, examples of the non-acidic particular aromaticcompound include aromatic hydrocarbon compounds such as toluene, xylene,naphthalene, biphenyl, and terphenyl; halogenated aromatic hydrocarboncompounds such as monochlorobenzene, dichlorobenzene, trichlorobenzene,dichlorotoluene, chloronaphthalene, and bromobenzene; aromatic nitrocompounds such as nitrobenznene and fluoronitrobenzene; aromatic estercompounds such as butyl benzoate, methyl chlorobenzoate, methylmethylbenzoate, and phenyl acetate; aromatic ether compounds such asdiphenyl ether, anisole, and chloroanisole; aromatic aldehyde compoundssuch as benzaldehyde and chlorobenzaldehyde; aromatic ketone compoundssuch as acetophenone and chloroacetophenone; heterocyclic aromaticcompounds such as thiophene, furan, quinoline, and picoline; and thelike.

Among these non-acidic particular organic compounds, in view of thecrystal form-converting ability, preferred are aliphatic compounds oraromatic compounds containing a halogen atom or an oxygen atom, oraromatic hydrocarbon compounds. Of these, in consideration of stabilityof the resulting phthalocyanine crystal at dispersing, more preferredare halogenated aliphatic compounds, aliphatic ether compounds,aliphatic ketone compounds, aliphatic ester compounds, aromatichydrocarbon compounds, halogenated aromatic compounds, aromatic nitrocompounds, aromatic ketone compounds, aromatic ester compounds, andaromatic aldehyde compounds. From the viewpoint of the properties of theelectrophotographic photoreceptor using the resulting phthalocyaninecrystal as a material, further preferred are aliphatic ether compounds,halogenated aromatic compounds, aromatic nitro compounds, aromaticketone compounds, aromatic ester compounds, and aromatic aldehydecompounds.

In this connection, these non-acidic particular organic compoundssometimes belong simultaneously to a plurality of compound groups of theaforementioned compound groups depending on the kind of the substituentand the like in the structure (for example, nitrochlorobenzene belongsto both of the “halogenated aromatic compound” and the “aromatic nitrocompound”) but such a non-alcoholic organic compound is judged as onehaving all the attributes of a plurality of these classifications (forexample, nitrochlorobenzene has attributes of both of the halogenatedaromatic compound and the aromatic nitro compound).

Moreover, the non-acidic particular organic compound is in a liquidstate under conditions of 1013 hPa (760 mmHg) and 25° C.

The molecular weight of the non-acidic particular organic compound isnot particularly limited but, since the viscosity or the like increaseswith the increase in the molecular weight and productivity decreases,the molecular weight of the non-acidic particular organic compound isusually 1000 or less, preferably 500 or less, more preferably 400 orless, further preferably 300 or less. On the other hand, when themolecular weight of the non-acidic particular organic compound is toosmall, the boiling point thereof is generally lowered and is easilyvaporized and thus the handling properties at production tends to beimpaired, so that a lower limit of the molecular weight is usually 50 ormore, preferably 100 or more.

Any one of the non-acidic particular organic compounds may be usedsingly or two or more thereof may be used in combination at anycombination and in any ratio.

[Combined Use of Electron-Withdrawing Particular Aromatic Compound andNon-Acidic Particular Organic Compound]

The mechanism why the existence of the electron-withdrawing particulararomatic compound at the conversion of the crystal form influences theproperties of the phthalocyanine crystal as an electrophotographicphotoreceptor is not clear. However, it is presumed that the advantagesof the invention is obtained by more efficient incorporation of theelectron-withdrawing particular aromatic compound into thephthalocyanine crystal realized by the co-existence of the non-acidicparticular organic compound and the electron-withdrawing particulararomatic compound.

[Particular Substituent-Containing Aromatic Compound]

The compound (D) for converting the crystal form is an aromatic compoundhaving an oxygen atom-containing group and a halogen atom having anatomic weight of 30 or more as substituents (hereinafter optionallyreferred to as “particular substituent-containing aromatic compound”).The particular substituent-containing aromatic compound is used as acontact compound for converting the crystal form.

As the aromatic skeleton of the particular substituent-containingaromatic compound, there may be mentioned aromatic hydrocarbon skeletonssuch as benzene, naphthalene, anthracene, phenanthrene, biphenyl, andterphenyl and heterocyclic aromatic skeletones such as pyrrole,thiophene, furan, pyridine, quinoline, isoquinoline, and phenanthroline.However, since the regulating ability into the aforementioned particularcrystal form that is a suitable crystal form in the phthalocyaninecrystal of the invention decreases when the aromatic skeleton portionhas heteroatom(s) such as nitrogen, oxygen, and/or sulfur, the aromatichydrocarbon skeleton is preferred. The particular substituent-containingaromatic compound is preferably in a liquid state at the time when it isbrought into contact with the phthalocyanine crystal precursor. Since itis difficult to be in a liquid state when the molecular weight of thearomatic skeleton portion is large, skeletons such as benzene,naphthalene, biphenyl, pyrrole, thiophene, furan, and pyridine areusually used. Of these, aromatic hydrocarbon skeletons such as benzene,naphthalene, and biphenyl are preferred. From the viewpoint of theelectrophotographic properties of phthalocyanine crystal, benzene isparticularly preferred.

Moreover, since the contact of the particular substituent-containingaromatic compound with the phthalocyanine crystal precursor is usuallycarried out at 100° C. or lower, the melting point of the particularsubstituent-containing aromatic compound is usually 100° C. or lower.When the melting point is too high, the handling property of theparticular substituent-containing aromatic compound decreases at thecontact with the phthalocyanine crystal precursor, so that the meltingpoint of the particular substituent-containing aromatic compound ispreferably 80° C. or lower, more preferably 60° C. or lower.

As the halogen atom having an atomic weight of 30 or more contained inthe particular substituent-containing aromatic compound, there may bementioned a chlorine atom, a bromine atom, or an iodine atom but, inview of the handling at the production, a chlorine atom and a bromineatom are preferred and, in view of the properties as anelectrophotographic photoreceptor, a chlorine atom is more preferred.

The halogen atom having an atomic weight of 30 or more contained in theparticular substituent-containing aromatic compound is usually directlybonded to the aromatic skeleton. The number of the halogen atoms havingan atomic weight of 30 or more is arbitrary but, since the freezingpoint elevates and the handling property at the production decreases asthe number of the halogen atoms increases, the number is preferably 3 orless and, in view of the sensitivity of the electrophotographicphotoreceptor, it is more preferably 2 or less. In particular, thecompound is particularly preferably a halogen-monosubstituted aromaticcompound.

The kind of the oxygen atom-containing group contained in the particularsubstituent-containing aromatic compound is not particularly limited butexamples thereof include a phenolic hydroxyl group; an aldehyde group; acarboxylic acid group; a nitroso group; a nitro group; an imidic acidgroup; a hydroximic acid group; a hydroxamic acid group; a cyanic acidgroup; an isocyanic acid group; an azoxy group; an amido group; acylgroups such as an acetyl group and a phenoxy group; ether groups such asa methoxy group, a benzyloxy group, and a phenoxy group; acetal groupssuch as dimethyl acetal group, a methyl ethyl acetal group, and anethylene acetal group. Of these groups, a group having a substituentcapable of being further substituted, such as an alkyl chain, may befurther substituted.

Of the above oxygen atom-containing groups, in view of thecrystal-regulating ability, substituents having a carbonyl group, suchas an aldehyde group, an ester group, an acyl group, and an acyloxygroup, a nitro group, and an ether group are preferred. In particular,an aldehyde group, a nitro group, an ether group, an ester group, anacyl group, and an acyloxy group are more preferred.

It is presumed that the crystal form-regulating ability at the contactwith the phthalocyanine crystal precursor is increased by the use of theparticular substituent-containing aromatic compound and the particularsubstituent-containing aromatic compound is incorporated into thephthalocyanine crystal precursor to thereby exhibit the advantages ofthe invention, so that the oxygen atom-containing group may be directlybonded to the aromatic ring and also may be bonded to the aromatic ringthrough a divalent organic residue (excluding an arylene group).

In the case where the oxygen atom-containing group is bonded to thearomatic ring through a divalent organic residue, the molecular volumeof the particular substituent-containing aromatic compound increases bythe organic residue and the compound is hardly incorporated intophthalocyanine crystal, so that the molecular weight of the organicresidue portion is usually 100 or less, preferably 50 or less. However,it is more preferred that the oxygen atom-containing group does not havethe divalent organic residue and is directly bonded to the aromatic ringthrough the oxygen atom like an ether group or the atom directly bondedto the aromatic ring has an oxygen atom, like the carbon atom of acarbonyl group or the nitrogen atom of a nitro group.

The molecular weight per oxygen atom-containing group is usually 300 orless. When the molecular weight is too large, the properties of theelectrophotographic photoreceptor decreases, so that the molecularweight is preferably 250 or less, more preferably 200 or less, furtherpreferably 150 or less.

When the number of the oxygen atom-containing groups contained in theparticular substituent-containing aromatic compound is too large, bothof the molecular weight and molecular volume of the particularsubstituent-containing aromatic compound increase and thus theadvantages obtained by the use of the particular substituent-containingaromatic compound decreases, so that the number is usually 5 or less,preferably 3 or less, more preferably 2 or less, and further preferably1.

In addition to the oxygen atom-containing group and the halogen atomhaving an atomic weight of 30 or more, the particularsubstituent-containing aromatic compound may have the othersubstituent(s) on the aromatic ring. As the other substituent, there maybe mentioned alkyl groups such as a methyl group, an ethyl group, anisopropyl group, and a cyclohexyl group; thioalkyl groups such as athiomethyl group and a thioethyl group; a cyano group; a mercapto group;substituted or unsubstituted amino groups such as an amino group, amonomethylamino group, and a methylethylamino group; halogenated alkylgroups such as a trifluoromethyl group; known substituents containing nooxygen atom, such as a fluorine atom; a halogen atom having an atomicweight of 29 or less; and the like.

Among the above examples of the other substituent, with regard to thesubstituents having a carbon chain, such as alkyl groups, substitutedalkyl groups, and halogenated alkyl groups, the carbon chain portion mayhave any structure of linear chain, branched chain, and cyclic one.However, when the structure of the carbon chain portion of thesesubstituents is too large, stability of the resulting phthalocyaninecrystal is adversely affected, so that the structure is preferably astructure of a linear or branched chain, more preferably a linear chain.Moreover, the carbon number of the carbon chain portion is usually 20 orless but, since the effect of the particular substituent-containingaromatic compound decreases when the carbon number of the carbon chainportion is too large, it is preferably 15 or less, more preferably 10 orless, further preferably 6 or less.

Among the above examples of the other substituent, in the considerationof the crystal-regulating ability at the crystal conversion, a fluorineatom or an alkyl group is preferred. In particular, since thecrystal-regulating ability at the crystal conversion decreases whenthree-dimensional molecular volume as a substituent increases, a methylgroup, an ethyl group, or a fluorine group is more preferred and amethyl group or a fluorine atom is further preferred.

In this connection, any one of the above particularsubstituent-containing aromatic compounds may be used singly or two ormore thereof may be used in combination at any combination and in anyratio.

Moreover, one or two or more particular substituent-containing aromaticcompounds may be mixed with one or two or more other compounds and thenbrought into contact with the phthalocyanine crystal precursor. In thiscase, the kind of the other compound to be used in combination with theparticular substituent-containing aromatic compound is not particularlylimited so long as it does not adversely affect the phthalocyaninecrystal precursor to be used and the resulting phthalocyanine crystal.However, in the case where the other compound other than the particularsubstituent-containing aromatic compound is used in combination, it ispreferred that the ratio of the particular substituent-containingaromatic compound to the total amount of the particularsubstituent-containing aromatic compound and the other compound isusually 50% by weight or more, particularly 75% by weight or more.

The amount of the particular substituent-containing aromatic compound tobe used varies depending on the method to be used in the contacttreatment and cannot be categorically defined but, in general, theweight ratio to the phthalocyanine crystal precursor is in the range ofusually 50% by weight or more, preferably 100% by weight or more andusually 2000% by weight or less, preferably 1000% by weight or less. Inthe case where two or more particular substituent-containing aromaticcompounds are used in combination, the total ratio of them is to fallwithin the above range.

[Crystal Form Conversion Step]

In the crystal form conversion step, the crystal form of thephthalocyanine crystal precursor is converted using the aforementionedcompound for converting the crystal form. Namely, the phthalocyaninecrystal precursor is brought into contact with the contact compound forconverting the crystal form in the presence of the co-existing compoundfor converting the crystal form to be used according to need, therebythe crystal form being converted.

In the crystal form conversion step, as mentioned above, any one of theabove compounds (A) to (D) for converting the crystal form may be usedsingly or two or more thereof may be used in combination at anycombination and in any ratio.

[Contact Procedure]

In the crystal form conversion step, the method for bringing thephthalocyanine crystal precursor into contact with at least one compoundfor converting the crystal form selected from the compounds forconverting the crystal form is not particularly limited and any knownmethod may be used.

In particular, the phthalocyanine crystal precursor is generally broughtinto contact with the compound for converting the crystal form in thepresence of water and the method is suitable for obtaining thephthalocyanine crystal of the invention. In the case of using water, theamount thereof is not particularly limited but the weight ratio to thecompound for converting the crystal form is preferably in the range ofusually 100% by weight or more, particularly 500% by weight or more andusually 5000% by weight or less, particularly 1500% by weight or less.In the case where two or more compounds for converting the crystal formare used in combination, it is preferred that the total ratio of them isto fall within the above range.

As the specific contact method of the compound for converting thecrystal form with the phthalocyanine crystal precursor, there may be,for example, mentioned a method of bringing the phthalocyanine crystalprecursor into contact with a vapor or liquid containing the compoundfor converting the crystal form or a solution containing the compoundfor converting the crystal form with stirring, a method of bringing thephthalocyanine crystal precursor into contact with the compound forconverting the crystal form with adding mechanical force together with amedium in an apparatus such as automatic mortar, planetary mill,vibration ball mill, CF mill, roller mill, sand mill, or kneader, andthe like method.

The temperature at the time when the compound for converting the crystalform is brought into contact with the phthalocyanine crystal precursoris not particularly limited but is usually 150° C. or lower. Therefore,all the contact compounds for converting the crystal form to be used inthe invention desirably have a melting point of usually 150° C. orlower. When the melting point of the contact compound for converting thecrystal form is too high, the handling property of the contact compoundfor converting the crystal form at the crystal conversion decreases, sothat it is preferably 120° C. or lower, more preferably 80° C. or lower.

By the contact treatment (i.e., crystal form conversion treatment) ofthe compound for converting the crystal form with the phthalocyaninecrystal precursor, the phthalocyanine crystal is obtained. The resultingphthalocyanine crystal of the invention may be washed using water andvarious organic solvents according to need. The phthalocyanine crystalof the invention obtained after the contact treatment or after washingis usually in a wet cake state. As mentioned above, since it isconsidered that the advantages of the invention are obtained by theincorporation of the compound for converting the crystal form into thephthalocyanine crystal at the time when the phthalocyanine crystalprecursor is brought into contact with the compound for converting thecrystal form at the crystal conversion, the content of thephthalocyanine in the wet cake (weight of the phthalocyanine relative tothe total weight of the wet cake) is not particularly limited and may beany amount.

The wet cake of the phthalocyanine crystal of the invention obtainedafter the contact treatment or after washing is usually subject to adrying step. As the drying method, it is possible to dry the wet cake bya known method such as air-blow drying, heat-drying, vacuum drying, orfreeze-drying.

The phthalocyanine crystal of the invention obtained by the above methodusually takes a form where primary particles are agglomerated to formsecondary particles. The particle diameter largely varies depending onthe conditions, formulation, and the like at the contact of the compoundfor converting the crystal form with the phthalocyanine crystalprecursor but, in consideration of dispersibility, the primary particlesize is preferably 500 nm or less, and in view of film-forming abilityby application, is preferably 250 nm or less.

In the invention, the definition whether the crystal conversion isachieved or not before and after the contact of the phthalocyaninecrystal precursor with the compound for converting the crystal form isas follows. Namely, the case where individual peaks of the powder X-raydiffraction spectra before and after the contact are entirely the sameis defined as no occurrence of crystal conversion and the case wheredifference in information of the peak positions, presence of the peaks,the peak half bandwidth, and the like is observed even a little isdefined as occurrence of crystal conversion.

[Crystal Form of Crystalline Phthalocyanine]

The crystal form of the phthalocyanine crystal of the invention may beany crystal form as far as it is a crystal form different from that ofthe phthalocyanine crystal precursor. Particularly, from the viewpointof the properties of the electrophotographic photoreceptor in the caseof using the phthalocyanine crystal as a material for theelectrophotographic photoreceptor, preferred is a crystal form which hasa main peak at Bragg angle (2θ±0.2°) of 27.2° toward CuKα characteristicX-ray (wavelength 1.541 angstrom) (hereinafter, optionally referred toas “particular crystal form”).

Although the mechanism for obtaining the advantages of the invention isno clear, it is considered that, at the time when the phthalocyaninecrystal precursor is brought into contact with the compound forconverting the crystal form to construct the crystal form, thephthalocyanine ring and the compound for converting the crystal forminteract with each other to incorporate the compound for converting thecrystal form into the phthalocyanine crystal and also the incorporatedcompound for converting the crystal form interacts with water present inthe crystal as a sensitizer to thereby suppress the elimination of waterfrom the inside of the crystal under a low humid condition, enable thepresence of the water molecule in the phthalocyanine crystal even underthe low humid condition, and suppress sensitivity decrease induced bythe elimination of water as a sensitizer or the compound for convertingthe crystal form plays a role as a sensitizer instead of the watermolecule which is a sensitizer.

In particular, since the above particular crystal form is low in crystaldensity and has a lot of vacant space portions in the crystal ascompared with the other crystal forms, the compound for converting thecrystal form is easily incorporated into the crystal at the time whenthe phthalocyanine crystal is brought into contact with the compound forconverting the crystal form to construct the aforementioned particularcrystal form.

In the case where the phthalocyanine crystal precursor is brought intocontact with the aromatic aldehyde compound to obtain the phthalocyaninecrystal of the invention, it is considered that, at the time when thecrystal form is constructed, the π electrons of the phthalocyanine ringand the aromatic ring portion of the aromatic aldehyde compound interactwith each other to incorporate the aromatic aldehyde compound into thephthalocyanine crystal and also the aldehyde group portion of theincorporated aromatic aldehyde compound interacts with water present inthe crystal as a sensitizer to thereby suppress the elimination of waterfrom the inside of the crystal under a low humid condition, enable thepresence of the water molecule in the phthalocyanine crystal even underthe low humid condition, and suppress sensitivity decrease induced bythe elimination of water as a sensitizer or the aldehyde group portionof the aromatic aldehyde compound plays a role as a sensitizer insteadof the water molecule which is a sensitizer.

In the case where the phthalocyanine crystal precursor is brought intocontact with the non-acidic organic compound in the presence of theparticular organic acid compound to obtain the phthalocyanine crystal ofthe invention, it is considered that, at the time when the crystal formis constructed, the particular organic acid compound is incorporatedinto the phthalocyanine crystal and also the incorporated particularorganic acid compound interacts with water present in the crystal as asensitizer to thereby suppress the elimination of water from the insideof the crystal under a low humid condition, enable the presence of thewater molecule in the phthalocyanine crystal even under the low humidcondition, and suppress sensitivity decrease induced by the eliminationof water as a sensitizer or the particular organic acid compound plays arole as a sensitizer instead of the water molecule which is asensitizer.

In particular, since the above particular crystal form is low in crystaldensity and has a lot of vacant space portions in the crystal ascompared with the other crystal forms, the particular organic acidcompound is easily incorporated into the phthalocyanine crystal andplays a role as a sensitizer in the phthalocyanine crystal at the timewhen the non-acidic organic compound is brought into contact with thephthalocyanine crystal precursor in the presence of the particularorganic acid compound to construct the aforementioned particular crystalform.

In the case where the phthalocyanine crystal precursor is brought intocontact with the non-acidic particular organic compound in the presenceof the electron-withdrawing particular aromatic compound to obtain thephthalocyanine crystal of the invention, it is considered that, at thetime when the crystal form is constructed, the electron-withdrawingparticular aromatic compound is incorporated into the phthalocyaninecrystal and also the incorporated electron-withdrawing particulararomatic compound interacts with water as a sensitizer present in thecrystal to thereby suppress the elimination of water from the inside ofthe crystal under a low humid condition, enable the presence of thewater molecule in the phthalocyanine crystal even under the low humidcondition, and suppress sensitivity decrease induced by the eliminationof water as a sensitizer or the electron-withdrawing particular aromaticcompound plays a role as a sensitizer instead of the water moleculewhich is a sensitizer.

In particular, since the above particular crystal form is low in crystaldensity and has a lot of vacant space portions in the crystal ascompared with the other crystal forms, the electron-withdrawingparticular aromatic compound is easily incorporated into thephthalocyanine crystal and plays a role as a sensitizer in thephthalocyanine crystal at the time when the non-acidic particularorganic compound is brought into contact with the phthalocyanine crystalprecursor in the presence of the electron-withdrawing particulararomatic compound to construct the aforementioned particular crystalform.

In the case where the phthalocyanine crystal precursor is brought intocontact with the particular substituent-containing aromatic compound toobtain the phthalocyanine crystal of the invention, it is consideredthat the above particular substituent-containing aromatic compound isexcellent in crystal form-regulating ability at the time when thecrystal form is converted into the particular crystal form because thecompound has a halogen atom having an atomic weight of 30 or more aswell as the particular substituent-containing aromatic compound isincorporated into the phthalocyanine crystal at the crystal conversionand the oxygen atom-containing group in the particularsubstituent-containing aromatic compound plays a role as a sensitizer inthe crystal.

In particular, since the above particular crystal form is low in crystaldensity and has a lot of vacant space portions in the crystal ascompared with the other crystal forms, the π electrons of thephthalocyanine ring and the aromatic ring portion of the particularsubstituent-containing aromatic compound interacts with each other tothereby incorporate the particular substituent-containing aromaticcompound easily into the phthalocyanine crystal and plays a role as asensitizer in the phthalocyanine crystal at the time when the particularsubstituent-containing aromatic compound is brought into contact withthe phthalocyanine crystal precursor to construct the aforementionedparticular crystal form.

For the above reasons, the phthalocyanine crystal of the inventiondesirably has the aforementioned particular crystal form.

In the case where the phthalocyanine crystal has the aforementionedparticular crystal form, as combinations of definite peaks showntogether with the peak at 27.2°, the following (i) to (iii) may bementioned.

-   (i) 9.6°, 24.1°, 27.2°-   (ii) 9.5°, 9.7°, 24.1°, 27.2°-   (iii) 9.0°, 14.2°, 23.9°, 27.1°

In particularly, among the combinations of the peaks of the above (i) to(iii), those showing the above combinations (i) or (ii) are preferredbecause of excellent crystal stability at dispersing.

Particularly, a crystal form having main diffraction peaks at 7.3°,9.6°, 11.6°, 14.2°, 18.0°, 24.1°, and 27.2° or a crystal form havingmain diffraction peaks at 7.3°, 9.5°, 9.7°, 11.6°, 14.2°, 18.0°, 24.2°,and 27.2° is more preferred from the viewpoint of dark decay andresidual potential in the case of using it as a material for anelectrophotographic photoreceptor.

In this connection, since a phthalocyanine crystal having a peak ataround 26.2° or 28.6° rearranges into the other crystal form atdispersing to invite decrease in electrophotographic properties, thephthalocyanine crystal of the invention preferably has no definite peakat around 26.2° or 28.6°.

As mentioned above, it is considered that the effect of the compound forconverting the crystal form in the phthalocyanine crystal of theinvention is obtained through the incorporation of the compound forconverting the crystal form into the phthalocyanine crystal by bringingthe phthalocyanine crystal precursor into contact with the compound forconverting the crystal form at the crystal conversion and is notdependent on the molecular orientation in the crystal. Thus, in thepreferable combination of the peaks mentioned above, it is consideredthat the intensity ratio between individual peaks does not correlate tothe advantages of the invention. Therefore, these peaks may have anyintensity ratio but usually, a peak at around 27.2° or a peak at around9.6° becomes largest in many cases.

[Chlorinated Oxytitanium Phthalocyanine]

In the case of oxytitanium phthalocyanine crystal (crystal or mixedcrystal containing at least oxytitanium phthalocyanine) suitable as thephthalocyanine crystal of the invention, oxytitanium phthalocyaninewhose phthalocyanine ring is chlorinated (chlorinated oxytitaniumphthalocyanine) is contained in the crystal in some cases. Since it isconsidered that the advantages of the invention are exhibited throughthe incorporation of the compound for converting the crystal form,existence of much space is preferred in the oxytitanium phthalocyaninecrystal so that a large amount of the compound for converting thecrystal form is incorporated. The chlorinated oxytitanium phthalocyaninehas a chloro group in the phthalocyanine ring portion and the molecularvolume increases as compared with unsubstituted oxytitaniumphthalocyanine. Therefore, when the chlorinated oxytitaniumphthalocyanine is present in the crystal, the space for incorporatingthe compound for converting the crystal form decreases. For the abovereason, the oxytitanium phthalocyanine for use in as a phthalocyaninecrystal precursor for the production of the crystalline oxytitaniumphthalocyanine (hereinafter abbreviated as “precursor for crystallineoxytitanium phthalocyanine”) preferably has a less content of thechlorinated oxytitanium phthalocyanine.

Although it is possible to measure the content of the chlorinatedoxytitanium phthalocyanine in the precursor for crystalline oxytitaniumphthalocyanine by any conventionally known analytical methods, thecontent can be determined by the elemental analysis and mass spectrummeasurement described in JP-2001-115054. As specific conditions for theelemental analysis and mass spectrum measurement, the followingconditions may be, for example, mentioned.

<Conditions for Measuring Chlorine Content (Elemental Analysis)>

A precursor for crystalline oxytitanium phthalocyanine is preciselyweighed in an amount of 100 mg and placed on a quartz board, which isthen completely combusted in a temperature-elevating electric furnace(e.g., QF-02 manufactured by Mitsubishi Chemical Corporation) and theresulting combustion gas is quantitatively absorbed in 15 ml of water.The resulting absorbed solution is diluted to 50 ml and subjected tochlorine analysis by ion chromatography (“DX-120” manufactured byDionex). The following shows conditions for the ion chromatography.

-   Column: Dionex Ion Pak AG12A+AS12A-   Eluent: 2.7 mM sodium carbonate (Na₂CO₃)/0.3 mM sodium hydrogen    carbonate (NaHCO₃)-   Flow rate: 1.3 ml/min-   Injection amount: 50 μl    <Conditions for Mass Spectrum Measurement>    (a) Sample Preparation

In a 50 mL glass vessel is placed 0.50 g of a precursor for crystallineoxytitanium phthalocyanine together with 30 g of glass beads (φ1.0 to1.4 mm) and 10 g of cyclohexanone, and the whole is subjected todispersion treatment using a dye dispersion testing machine (paintshaker) for 3 hours, whereby a 5% by weight dispersion liquid ofoxytitanyl phthalocyanine is formed. One μl of the 5% by weightdispersion liquid of oxytitanium phthalocyanine is put in a 20 ml samplevial and 5 ml of chloroform is added thereto. The product is thenultrasonically dispersed for 1 hour, whereby a 10 ppm dispersion liquidof oxytitanium phthalocyanine is prepared.

(b) Measuring Apparatus/Conditions:

-   Measuring apparatus: JMS-700/MStaion manufactured by JEOL Corp.-   Ionization mode: DCI(−)-   Reaction gas: isobutane (pressure in ionization chamber: 1×10⁻⁵    Torr)-   Filament rate: 0→0.90 A (1 A/min)-   Mass spectrometric ability: 2000-   Scanning method: MF-Linear-   Scanning mass range: 500 to 600-   Time for scanning the whole mass range: 0.8 second-   Cycle time: 0.5 second    (c) Method for Calculating Mass Spectrum Peak Intensity Ratio of    Chlorinated Oxytitanium Phthalocyanine to Unsubstituted Oxytitanium    Phthalocyanine:

One μl of the 10 ppm dispersion liquid of oxytitanium phthalocyanineprepared in the above procedure was applied onto the filament of the DCIprobe and subjected to mass spectrum measurement under theaforementioned conditions. Based on the obtained mass spectrum, a ratioof the peak area at m/z=610, which corresponds to molecular ions of thechlorinated oxytitanyl phthalocyanine, to the peak area at m/z=576,which corresponds to molecular ions of the nonsubstituted oxytitanylphthalocyanine, obtained from the ion chromatography (“610” peakarea/“576” peak area) is calculated as a mass spectrum peak intensityratio.

The amount of the chlorinated oxytitanyl phthalocyanine contained in thecrystalline oxytitanyl phthalocyanine precursor, which is obtained bythe measurement based on the aforementioned <Conditions for MeasuringChlorine Content (Elemental Analysis)>, is preferably 0.4% by weight orless, more preferably 0.3% by weight or less, further preferably 0.2% byweight or less.

Moreover, the mass spectrum peak intensity ratio of the chlorinatedoxytitanyl phthalocyanine to the nonsubstituted oxytitanylphthalocyanine, which is obtained by the measurement based on theaforementioned <Conditions for Mass Spectrum Measurement>, is preferably0.050 or less, more preferably 0.040 or less, more preferably 0.030 orless.

[Others]

The mechanism why the use of the compound for converting the crystalform influences the properties of the phthalocyanine crystal as anelectrophotographic photoreceptor is not clear. However, as mentionedabove, it is considered that the advantages of the invention areobtained by the incorporation of the compound for converting the crystalform into the phthalocyanine crystal at the crystal conversion.

The amount of the compound for converting the crystal form to beincorporated into the crystal varies depending on the production processand is not particularly limited. However, the amount is usually 0.1 partby weight or more per 100 parts by weight of the phthalocyanine crystal.Particularly, since the advantages of the invention decreases when theincorporated amount of the compound for converting the crystal form issmall, the amount is preferably 0.2 part by weight or more, morepreferably 0.3 part by weight or more. However, since stability of thephthalocyanine crystal decreases when the incorporated amount of thecompound for converting the crystal form is too large, the amount ispreferably 10 parts by weight or less, more preferably 7 parts by weightor less. In this connection, in the case where a plurality of thecompounds for converting the crystal form are present in thephthalocyanine crystal, it is preferred that the total amount fallswithin the above range.

The content of the contact compound for converting the crystal form inthe phthalocyanine crystal can be calculated by the measurementaccording to a known gravimetric analysis. In particular, thephthalocyanine crystal having the aforementioned particular crystal formis known to cause crystal transformation at around 220 to 270° C. andthe compound contained in the crystal is released at the crystaltransformation. Accordingly, in the thermal gravimetric analysis of thephthalocyanine crystal having the aforementioned particular crystalform, it is possible to calculate the amount of the contact compound forconverting the crystal form contained based on the weight differencebefore and after the crystal transformation (e.g. the weight differencebetween 200° C. and 300° C.)

<Properties of Electrophotographic Photoreceptor>

The characteristics of the electrophotographic photoreceptor of theinvention lies in small half-decay exposure and high sensitivity as wellas very little fluctuation of photo-induced discharge characteristicsfor a humidity change.

The smaller half-decay exposure enables decrease in energy of exposinglight in the image-forming device such as a printer or a copying machineand hence consuming electric power of light source can be reduced, sothat the case is preferred. An electrophotographic photoreceptor usuallyhas different electric capacitance depending on film thickness of thesensitive layer and hence, when the film thickness is different, theamount of the surface charge is different even at the same potential.Namely, the half-decay exposure of the photoreceptor when quantumefficiency is 1 varies depending on the film thickness.

In the invention, the technical concepts that the half-decay exposure issmall and the sensitivity is high as well as the fluctuation of thephoto-induced discharge characteristics by humidity is extremely littleare common but, for the above reasons, the half-decay exposure E1/2 andthe degree of fluctuation of the photo-induced discharge characteristicsby humidity in the invention are defined with classifying the filmthickness and considering the half-decay exposure when the quantumefficiency is 1. Thereby, it is possible to define theelectrophotographic photoreceptor where the properties for theimage-forming device are particularly suitable in that film thickness.

In the case of the photoreceptor wherein the thickness of the sensitivelayer is 35±2.5 μm, the half-decay exposure E1/2 at a temperature of 25°C. and a relative humidity of 50% rh is usually 0.059 or less,preferably 0.054 or less, more preferably 0.051 or less, most preferably0.049 or less.

In the case of the photoreceptor wherein the thickness of the sensitivelayer is 30±2.5 μm, the half-decay exposure E1/2 at a temperature of 25°C. and a relative humidity of 50% rh is usually 0.061 or less,preferably 0.056 or less, more preferably 0.053 or less, most preferably0.051 or less.

In the case of the photoreceptor wherein the thickness of the sensitivelayer is 25±2.5 μm, the half-decay exposure E1/2 at a temperature of 25°C. and a relative humidity of 50% rh is usually 0.066 or less,preferably 0.061 or less, more preferably 0.058 or less, most preferably0.055 or less.

In the case of the photoreceptor wherein the thickness of the sensitivelayer is 20±2.5 μm, the half-decay exposure E1/2 at a temperature of 25°C. and a relative humidity of 50% rh is usually 0.079 or less,preferably 0.073 or less, more preferably 0.069 or less, most preferably0.066 or less.

In the case of the photoreceptor wherein the thickness of the sensitivelayer is 15±2.5 μm, the half-decay exposure E1/2 at a temperature of 25°C. and a relative humidity of 50% rh is usually 0.090 or less,preferably 0.083 or less, more preferably 0.079 or less, most preferably0.075 or less.

However, with regard to the half-decay exposure E1/2 in the invention,exposure of light (μJ/cm²) having a wavelength of 780 nm necessary fordecaying an absolute value |V0| of the surface potential V0 of anelectrophotographic photoreceptor from 550 V to 275 V is defined as thehalf-decay exposure E1/2. The measuring method will be mentioned belowin the article of <Measuring Method of Half-Decay Exposure Energy E1/2>.

The film thickness of the sensitive layer in the invention refers to thefilm thickness of the total of the charge generation layer and thecharge transport layer in the case of the multilayer photoreceptor andrefers to the film thickness of the sensitive layer in the case of thesingle-layer photoreceptor. In the case where the surface protectivelayer is present, the film thickness including the surface protectivelayer is regarded as the film thickness of the photoreceptor layer. Inthe case where layers other than the charge generation layer, the chargetransfer layer, the single-layer sensitive layer, and the surfaceprotective layer are present (e.g., an intermediate layer), the filmthickness of the layers are not included in the film thickness of thephotosensitive layer. It is possible to measure the film thickness byvarious methods but, for example, it is possible to measure it usingSurfcom 570A manufactured by Tokyo Seimitsu Co., Ltd.

The fluctuation of the photo-induced discharge characteristics for ahumidity change is preferably little, in the invention, when thephoto-induced discharge curve at a temperature of 25° C. and a relativehumidity of 50% rh is compared with the photo-induced discharge curve ata temperature of 25° C. and a relative humidity of 10% rh, but anabsolute value of the difference of the surface potential at the sameexposure (hereinafter referred to as “environmental fluctuationdependence”, the measuring method of which will be mentioned in thearticle of “Environmental Fluctuation Dependence”) is usually 50 V orless, preferably 40 V or less, more preferably 35 V or less, furtherpreferably 30 V or less, and suitably 20 V or less within the rangewhere the exposure is 0 to 10 times the half-decay exposure E1/2. Thesmaller the environmental fluctuation dependence is, the smaller theimage deterioration derived from the environmental fluctuation is.

When such an electrophotographic photoreceptor is used in a processcartridge or an image-forming device, a large number of sheets can beprinted per unit time and also consuming electric power is little andimage defects derived from the environmental fluctuation can be reduced.

In the invention, the measuring environment for the half-decay exposureE1/2 and photo-induced discharge curve are defined by the temperatureand relative humidity but the measurement is desirably carried out in anenvironment where an error is as little as possible.

The methods for measuring the temperature and relative humidity are notparticularly limited but usually, they are measured by a method inaccordance with the method standardized by Japanese Industrial Standards(JIS). For the temperature, the measuring method is defined in JISZ8704, Z8705, and Z8707 and, for the humidity, the measuring method isdefined in JIS Z8806.

Specifically, with regard to the temperature, when it falls within therange of ±2° C. of the temperature defined in the invention, thetemperature is judged to correspond to the temperature defined in theinvention.

Moreover, with regard to the humidity, when it falls within the range of±5% of the humidity defined in the invention in terms of relativehumidity, the humidity is judged to correspond to the humidity definedin the invention.

<Measuring Method of Half-Decay Exposure Energy E1/2>

The half-decay exposure ½ in the invention is a value measured using acommercially available photoreceptor evaluating apparatus (Cynthia 55,manufactured by Gentec Co.) in a static mode.

Specifically, it is measured by the procedure illustrated in thefollowing.

A charging device is disposed at an angle of 0°, an exposing device anda surface potentiometer probe at an angle of 90°, and an erasing deviceat an angle of 270° C. The charging device, surface potentiometer probe,and erasing device are disposed so that the distance from thephotoreceptor surface is 2 mm.

First, the photoreceptor is electrically charged in a dark place bybeing passed at a constant rotation speed (30 rpm) on a scorotroncharging device, which is set in such a manner that the electricaldischarge is carried out so that the surface potential of thephotoreceptor is adjusted to be about −700 V. When the photoreceptorsurface after electrical charging reaches the probe position, it isstopped and, 2.5 seconds after it is stopped, it is irradiated withmonochromatic light of 780 nm obtained from an attached spectroscopiclight source system POLAS34 in the intensity of 0.15 μW/cm² for 7.5seconds. At this time, the exposure required for decreasing the surfacepotential of the photoreceptor from −550 V to −275 V is measured. Afterthe photoreceptor is again rotated and subjected to full arc erase bythe erasing device, the same operations are carried out. The cycle isrepeated six times and the measured values of the exposure obtained in 5cycles excluding first cycle are averaged and the resulting averagevalue is determined as half-decay exposure E1/2 (μJ/cm²).

Although the case of a negatively charged photoreceptor is illustratedas an example in the above, it is suitable to make the potentialpositive in the case of a positively charged photoreceptor.

In this connection, after the photoreceptor to be measured is allowed tostand under the environment of a temperature of 25° C.±2° C. and ahumidity of 50%±5% for 5 hours or more, the measurement of thehalf-decay exposure E1/2 is carried out under the same environment.

<Measuring Method of Environmental Fluctuation Dependence>

The environmental fluctuation dependence in the invention is obtained bymounting the photoreceptor on an electrophotographic property evaluatingapparatus, which is manufactured according to the standard of theSociety of Electrophotography [“Zoku Denshishashin Gijutsu No Kiso ToOuyou”, edited by the Society of Electrophotography, issued by CoronaPublishing Co. Ltd, pp. 404-405] and evaluating electrical propertiesthrough a cycle of charging, exposure, measurement of potential, anderase. Specifically, it is determined by the procedure illustrated inthe following.

A charging device is disposed at an angle of −70°, an exposing device atan angle of 0° C., a surface potentiometer probe at an angle of 36°, andan erasing device at an angle of −150° C. Individual devices aredisposed so that the distance from the photoreceptor surface is 2 mm.For the charging, a scorotron charging device is used. As an exposinglamp, a halogen lamp JDR110V-85WLN/K7 manufactured by Ushio, Inc. isused and monochromatic light of 780 nm is formed using a filter MX0780manufactured by Asahi Bunko. LED light of 660 nm is used as an erasinglight.

The photoreceptor is charged with rotation at a constant rotation speed(60 rpm) so that an absolute value of initial surface potential of thephotoreceptor is 700 V (+700 V in the case of a positively chargedphotoreceptor and −700 V in the case of a negatively chargedphotoreceptor). When the charged photoreceptor surface passes through anexposure portion irradiating with monochromatic light of 780 nm andreaches the probe position, the surface potential is measured (time forexposure to potential measurement: 100 ms). The monochromatic light of780 nm is passed through ND filter to change light intensity, thephotoreceptor is irradiated with the light in an exposure 0 to 10 timesthe half-decay exposure E1/2, and surface potential is measured at eachexposure. The operations are carried out under the environment of atemperature of 25° C.±2° C. and a relative humidity of 50% rh±5%(hereinafter suitably sometimes referred to as “NN environment”) andpotential after exposure under the NN environment (hereinafter suitablysometimes referred to as “V_(NN)”) at each exposure is measured.

Thereafter, the same operations are carried out under the environment ofa temperature of 25° C.±2° C. and a relative humidity of 10% rh±5%(hereinafter suitably sometimes referred to as “NL environment”) andpotential after exposure under the NL environment (hereinafter suitablysometimes referred to as “V_(NL)”) at each exposure is measured.

An absolute value (|V_(NN)−V_(NL)|) of the difference between thepotential V_(NN) after exposure under the NN environment and thepotential V_(NL) after exposure under the NL environment at the sameexposure is calculated and the maximum value is determined asenvironmental fluctuation dependence.

In this connection, at the measurement of the potential after exposureunder the NN environment and the NL environment, it is carried out afterthe photoreceptors to be measured are allowed to stand under the NNenvironment (a temperature of 25° C.±2° C. and a humidity of 50% rh±5%)and under the NL environment (a temperature of 25° C.±2° C. and ahumidity of 10% rh±5%) for 5 hours or more, respectively.

<Measuring Method of Sensitivity Retention>

The sensitivity retention for a humidity change (hereinafter, optionallysometimes referred to as “sensitivity retention”) in the invention isobtained by evaluating electrical properties through a cycle ofcharging, exposure, measurement of potential, and erase using the samemeasuring apparatus as in the above measuring method of theenvironmental fluctuation dependence under the same measuring apparatusconditions.

The photoreceptor is charged with rotation at a constant rotation speed(60 rpm) so as that an absolute value of initial surface potential ofthe photoreceptor is 700 V (+700 V in the case of a positively chargedphotoreceptor and −700 V in the case of a negatively chargedphotoreceptor). When the charged photoreceptor surface passes through anexposure portion irradiating with monochromatic light of 780 nm andreaches the probe position, the surface potential is measured (time forexposure to potential measurement: 100 ms). The monochromatic light of780 nm is passed through ND filter to change light intensity, thephotoreceptor is irradiated with the light, and irradiation energy(exposure) is measured when surface potential is 350 V as an absolutevalue of initial surface potential (+350 V in the case of a positivelycharged photoreceptor and −350 V in the case of a negatively chargedphotoreceptor).

A value obtained by measuring the irradiation energy (exposure) underthe NN environment (unit: μJ/cm²) is regarded as standard humiditysensitivity (hereinafter optionally sometimes referred to as “En_(1/2)”)and a value obtained by measuring the irradiation energy (exposure)under the NL environment (unit: μJ/cm²) is regarded as low humiditysensitivity (hereinafter optionally sometimes referred to as“El_(1/2)”).

In this connection, as in the case of the above measuring method of theenvironmental fluctuation dependence, at the measurement of thepotential after exposure under the NN environment and the NLenvironment, it is carried out after the photoreceptors to be measuredare allowed to stand under the NN environment and under the NLenvironment for 5 hours or more, respectively.

The sensitivity retention for a humidity change is calculated bycalculation according to the following equation using the resultingstandard humidity sensitivity En_(1/2) and low humidity sensitivityEl_(1/2) (unit: %).Sensitivity retention (%) for humidity change=Standard humiditysensitivity En _(1/2) (μJ/cm²)/low humidity sensitivity El _(1/2)(μJ/cm²)×100  [Num 2][II. Electrophotographic Photoreceptor]

The following will describe the electrophotographic photoreceptor of theinvention. The electrophotographic photoreceptor of the invention is anelectrophotographic photoreceptor having a photosensitive layer formedon an electroconductive substrate and satisfying the above properties oran electrophotographic photoreceptor containing the phthalocyaninecrystal of the invention in the photosensitive layer.

[II-1. Electroconductive Substrate]

As the electroconductive substrate, there may be mainly used a metalmaterial such as aluminum, aluminum alloy, stainless steel, copper, ornickel; a resin material to which electroconductivity is imparted bybeing mixed with an electroconductive powder such as metal, carbon, ortin oxide; or a resin, glass, or paper material on whose surface anelectroconductive material such as aluminum, nickel, or ITO (indiumoxide tin oxide alloy) is vapor-deposited or applied. Its shape may be,for example, a drum shape, a sheet shape, a belt shape, etc. Besides, itis also possible to use an electroconductive substrate made of a metalmaterial whose surface is coated with an electroconductive materialhaving an appropriate resistance value for controlling properties suchas electroconductivity and surface nature as well as for defectcovering.

The surface of the electroconductive substrate may be smooth, or may beroughened using a special cutting method or a grinding treatment.Alternatively, it may also be roughened by mixing a materialconstituting the substrate with particles having appropriate particlesize. Moreover, it is also possible to use a drawn tube as it is withoutconducting cutting treatment in order to reduce cost. Particularly, inthe case of using uncut aluminum base material obtained by drawingprocess, impact process, ironing, or the like, the case is preferredsince attached matter such as stain and foreign matter present on thesurface, small scratches, and the like disappear and a uniform and cleanbase material is obtained.

When a metal material such as aluminum alloy is used as theelectroconductive substrate, it may be used after anodic oxidation filmformation. The anodic oxidation film is formed by anodic oxidationtreatment in an acidic bath such as chromic acid, sulfuric acid, oxalicacid, boric acid, or sulfamic acid but the anodic oxidation treatment insulfuric acid affords better results. In the case of the anodicoxidation in sulfuric acid, it is preferred that the sulfuric acidconcentration is set in the range of 100 to 300 g/l, the dissolvingaluminum concentration in the range of 2 to 15 g/l, the liquidtemperature in the range of 15 to 30° C., the electrolysis voltage inthe range of 10 to 20 V, the current density in the range of 0.5 to 2A/dm² but they are not limited to the above conditions.

When the average film thickness of the anodic oxidation film is toothick, higher concentration of a sealing liquid and stronger sealingconditions such as high-temperature/long-term treatment are required.Therefore, productivity becomes worse and also surface defects such asspecks, stains, and powdering tend to occur on the film surface. Fromsuch viewpoints, the anodic oxidation film is preferably formed in anaverage film thickness of usually 20 μm or less, particularly 7 μm orless.

In the case where the anodic oxidation film is formed, sealing treatmentis preferably carried out. The sealing treatment may be carried out by ausual method but, for example, a low-temperature sealing treatment ofimmersion in an aqueous solution containing nickel fluoride as a maincomponent or a high-temperature sealing treatment of immersion in anaqueous solution containing nickel acetate as a main component ispreferably carried out.

In the case of the low-temperature sealing treatment, the concentrationof an aqueous nickel fluoride solution to be used can be suitablyselected but more preferable result is obtained particularly in therange of 3 to 6 g/l. The pH of the aqueous nickel fluoride solution maybe usually 4.5 or higher, preferably 5.5 or higher and usually 6.5 orlower, preferably 6.0 or lower for the treatment. As a pH regulator,there may be used oxalic acid, boric acid, formic acid, acetic acid,sodium hydroxide, sodium acetate, aqueous ammonia, and the like.Moreover, for further improving physical properties of the film, cobaltfluoride, cobalt acetate, nickel sulfate, a surfactant, or the like maybe added to the aqueous nickel fluoride solution. For smooth sealingtreatment, the treating temperature may be in the range of usually 25°C. or higher, preferably 30° C. or higher and usually 40° C. or lower,preferably 35° C. or lower. The treating time is preferably in the rangeof 1 to 3 minutes per 1 μm of the thickness of the film. Then, thelow-temperature sealing treatment is finished after washing with waterand drying.

In the case of the high-temperature sealing treatment, as the sealingagent, an aqueous solution of a metal salt such as nickel acetate,cobalt acetate, lead acetate, nickel acetate-cobalt, or barium nitratecan be used but particularly, nickel acetate is preferably used. In thecase of using the aqueous nickel acetate solution, it is preferably usedin the concentration range of usually 5 to 20 g/l. The pH of the aqueousnickel acetate solution is preferably in the range of usually 5.0 to 6.0for the treatment. As the pH regulator, aqueous ammonia, sodium acetate,or the like can be used. For improving the physical properties of thefilm, sodium acetate, an organic carboxylic acid, an anionic or nonionicsurfactant, or the like may be added to the aqueous nickel acetatesolution. The treating temperature is in the range of usually 80° C. orhigher and usually 100° C. or lower, preferably 90° C. or higher andpreferably 98° C. or lower. The treating time is usually 10 minutes ormore, preferably 20 minutes or more. Then, the high-temperature sealingtreatment is finished after washing with water and drying.

[II-2. Undercoat Layer]

Between the electroconductive substrate and the below-mentionedphotosensitive layer, an undercoat layer may be formed for the purposeof improving properties such as adhesive property and blocking property.As the undercoat layer, a binder resin, a material obtained bydispersing particles of a metal oxide or the like into the binder resin,or the like is used.

Examples of metal oxide particles usable for the undercoat layer includemetal oxide particles containing a single metal element, such astitanium oxide, aluminum oxide, silicon oxide, zirconium oxide, zincoxide, iron oxide, etc.; and metal oxide particles containing aplurality of metal elements, such as calcium titanate, strontiumtitanate, barium titanate, etc. One kind of these metal oxide particlesmay be used singly or plural kinds thereof may be used as a mixture atany combination and in any ratio. Among these metal particles, titaniumoxide and aluminum oxide are preferred and particularly, titanium oxideis preferred. The titanium oxide particles may be subjected to thetreatment with an inorganic substance such as tin oxide, aluminum oxide,antimony oxide, zirconium oxide, or silicon oxide or an organicsubstance such as stearic acid, a polyol, or a silicone. As a crystalform of the titanium oxide particles, any of rutile, anatase, brookite,and amorphous can be used. Moreover, those containing plural crystalstates may be contained.

The metal oxide particles can be arbitrarily selected from a widevariety of particle sizes, although their average primary particle sizeis preferred to be within the range of usually 10 nm or more and usually100 nm or less, particularly 50 nm or less, in view of the propertiesand the stability of the liquid.

It is desired to form the undercoat layer in such a manner that theabove metal oxide particles are dispersed in binder resin. Examples ofbinder resin used for the undercoat layer include known binder resins,e.g., epoxy resins, polyethylene resins, polypropylene resins, acrylicresins, methacrylic resins, polyamide resins, vinyl chloride resin,vinyl acetate resin, phenol resins, polycarbonate resins, polyurethaneresins, polyimide resins, vinylidene chloride resins, polyvinyl acetalresins, vinyl chloride-vinyl acetate copolymers, polyvinyl alcoholresins, polyurethane resins, polyacrylic acid resins, polyacrylamideresins, polyvinylpyrrolidone resins, polyvinylpyridine resins,water-soluble polyester resins, cellulose ester resins such asnitrocellulose, cellulose ether resins, casein, gelatin, polyglutamicacid, starch, starch acetate, amino starch, organic zirconium compoundssuch as zirconium chelate compound and zirconium alkoxide compound,organic titanyl compounds such as titanyl chelate compound and titanylalkoxide compound, silane coupling agents, and the like. They may beused singly, or may be used in the form of being hardened with ahardening agent. Among them, alcohol-soluble copolymerized polyamidesand modified polyamides exhibit good dispersibility and coatability andare therefore preferred.

The mixing ratio of the metal oxide particles to the binder resin can bearbitrarily selected but the ratio is preferably in the range of usually10% by weight or more and 500% by weight or less in view of thestability and coatability of the dispersion liquid.

In addition, for the purpose of preventing image defects, pigmentparticles, resin particles, and the like may be contained in theundercoat layer.

The thickness of the undercoat layer can be selected arbitrarily, butthe thickness is preferably in the range of usually 0.01 μm or more,preferably 0.1 μm or more and usually 30 μm or less, preferably 20 μm orless from the viewpoint of the properties of the photoreceptor and thecoatability.

[II-3. Photosensitive Layer]

A photosensitive layer is formed on the electroconductive substrate(when the aforementioned undercoat layer is formed, on the undercoatlayer). The photosensitive layer comprises a charge generationsubstance, a charge transport substance, and a binder resin.

As the structure of the photosensitive layer, there may be mentioned aphotosensitive layer having a single layer structure (hereinafter,optionally referred to as “single-layer photosensitive layer”) in whichthe charge generation substance and the charge transport substance arepresent in the same layer with being dispersed in binder resin and afunction-separated photosensitive layer having a layered structure(hereinafter also called “multilayer photosensitive layer”) comprising acharge generation layer in which the charge generation substance isdispersed in binder resin and a charge transport layer in which thecharge transport substance is dispersed in binder resin. Both of thesetypes can be used. In the case of the multilayer photosensitive layer,there can be mentioned a normally-layered photosensitive layer whereinthe charge generation layer and the charge transport layer are layeredin the named order from the side of the electroconductive substrate andan inversely-layered photosensitive layer wherein the charge transportlayer and the charge generation layer are layered in the named orderfrom the side of the electroconductive substrate. Any of them can beadopted. The following will explain each structure.

<Charge Generation Layer of Multilayer Photosensitive Layer>

The charge generation layer of the multilayer photosensitive layer isformed according to a method wherein a binder resin is dissolved ordispersed in a solvent or a dispersion medium and also a chargegeneration substance is dispersed to prepare a coating solution and thecoating solution is applied onto the electroconductive substrate (whenthe undercoat layer is formed, onto the undercoat layer) in the case ofthe normally-layered photoreceptor or onto the charge transport layer inthe case of the inversely-layered photoreceptor so that fine particlesof the charge generation substance is bound by the binder resin.

Charge Generation Substance:

As the charge generation substance, any conventionally known chargegeneration substances can be used so long as they satisfy the gist ofthe invention. Preferably, the phthalocyanine crystal of the inventionis used. In the case of using the phthalocyanine crystal of theinvention, any one may be used singly or two or more thereof may be usedin combination at any combination and in any ratio. Moreover, thephthalocyanine crystal of the invention alone may be used as the chargegeneration substance but the phthalocyanine crystal of the invention maybe combined with the other charge generation substance and they may bealso used in a mixed state.

The particle size of the phthalocyanine crystal of the invention to beused as the charge generation substance is preferably sufficientlysmall. Specifically, it is used in a size of preferably 1 μm or less,more preferably 0.5 μm or less.

As the other charge generation substances that is used in a mixed statewith the phthalocyanine crystal of the invention, known various dyes andpigments may be mentioned. Examples of the dyes and pigments includephthalocyanine pigments, azo pigments, dithioketopyrrolopyrrolepigments, squalene (squalilium pigments), quinacridone pigments, indigopigments, perylene pigments, polycyclic quinone pigments, anthanthronepigments, benzimidazole pigments, and the like. Of these, phthalocyaninepigments and azo pigments are preferred in view of light sensitivity. Inthis connection, any one of the other charge generation substances maybe used singly or two or more thereof may be used in combination at anycomposition and combination.

Binder Resin:

The kind of the binder resin used for the charge generation layer is notparticularly limited and examples thereof include insulating resins,e.g., polyvinyl butyral resins, polyvinyl formal resins, polyvinylacetal resins such as partly-acetalized polyvinyl butyral resins (inwhich a part of the butyrals is modified by formals, acetals, or thelikes), polyarylate resins, polycarbonate resins, polyester resins,modified ether-based polyester resins, phenoxy resins, polyvinylchloride resins, polyvinylidene chloride resins, polyvinyl acetateresins, polystyrene resins, acrylic resins, methacrylic resins,polyacrylamide resins, polyamide resins, polyvinylpyridine resins,cellulose-based resins, polyurethane resins, epoxy resins, siliconeresins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, casein,vinyl chloride/vinyl acetate-based copolymers such as vinylchloride/vinyl acetate copolymers, hydroxyl-modified vinylchloride/vinyl acetate copolymers, carboxyl-modified vinylchloride/vinyl acetate copolymers, and vinyl chloride/vinylacetate/maleic anhydride copolymers, styrene/butadiene copolymers,vinylidene chloride/acrylonitrile copolymers, styrene/alkyd resins,silicone/alkyd resins, and phenol/formaldehyde resins, as well asorganic photoconductive polymers such as poly-N-vinylcarbazole,polyvinylanthracene, and polyvinylperylene. The binder resin can beselected from them and used but is not limited these polymers. Any ofthese binder resins may be used singly or two or more thereof may beused in combination at any combination and in any ratio.

Mixing Ratio:

In the charge generation layer, the mixing ratio (by weight) of thecharge generation substance to the binder resin is, relative to 100parts by weight of the binder resin, in the range of usually 10 parts byweight or more, preferably 30 parts by weight or more and usually 1000parts by weight or less, preferably 500 parts by weight or less. Whenthe ratio of the charge generation substance is too high, the stabilityof the coating solution may decline due to, e.g., the agglomeration ofthe charge generation substance, while when the ratio is too low, thesensitivity as the photoreceptor may decrease. It is hence preferredthat the substance is used within the above-mentioned range.

Solvent or Dispersion Medium:

As the solvent or dispersion medium to be used for preparing a coatingsolution, examples thereof include saturated aliphatic solvents such aspentane, hexane, octane, and nonane; aromatic solvents such as toluene,xylene, and anisole; halogenated aromatic solvents such aschlorobenzene, dichlorobenzene, and chloronaphthalene; amide-basedsolvents such as dimethyl formamide and N-methyl-2-pyrrolidone;alcohol-based solvents such as methanol, ethanol, isopropanol,n-butanol, and benzil alcohol; aliphatic polyhydric alcohols such asglycerin and polyethyleneglycol; chain and cyclic ketone-based solventssuch as acetone, cyclohexanone, and methyl ethyl ketone,4-methoxy-4-methyl-2-pentanon; ester-based solvents such as methylformate, ethyl acetate, and n-butyl acetate; halogenated hydrocarbonsolvents such as methylene chloride, chloroform, and 1,2-dichloroethane;chain and cyclic ether-based solvents such as diethyl ether,dimethoxyethane, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, andethyl cellosolve; aprotic polar solvents such as acetonitrile,dimethylsulfoxide, sulfolane, and hexamethylphosphoric triamide;nitrogen-containing compounds such as n-butylamine, isopropanolamine,diethylamine, triethanolamine, ethylenediamine, triethylenediamine, andtriethylamine; mineral oils such as ligroin; water; and the like. Amongthem, preferred are those that do not dissolve the above undercoatlayer. Any one of these solvents and dispersion media may be used singlyor two or more thereof may be used in combination at any combination andin any ratio.

Procedure for Dispersion:

As the method for dispersing the charge generation substance in thesolvent or dispersion medium, any known dispersion method such as a ballmil dispersion method, an attritor dispersion method, or a sand milldispersion method can be used. On this occasion, it is effective topulverize the charge generation substance to a particle size of usually0.5 μm or less, preferably 0.3 μm or less, more preferably 0.15 μm orless.

Film Thickness:

The film thickness of the charge generation layer is in the range ofusually 0.1 μm or more, preferably 0.15 μm or more and usually 10 μm orless, preferably 0.6 μm or less.

<Charge Transport Layer of Multilayer Photosensitive Layer>

The charge transfer layer of the multilayer photosensitive layer isformed according to a method wherein a binder resin is dissolved ordispersed in a solvent or a dispersion medium and also a chargetransport substance is dispersed thereinto to prepare a coating solutionand the coating solution is applied onto the charge transport layer inthe case of the normally-layered photoreceptor or onto theelectroconductive substrate (when the undercoat layer is formed, ontothe undercoat layer) in the case of the inversely-layered photoreceptorso that fine particles of the charge transport substance is bound by thebinder resin.

Binder Resin:

Examples of the binder resin include polymers and copolymers of vinylcompounds such as butadiene resins, styrene resins, vinyl acetateresins, vinyl chloride resins, acrylic acid ester resins, methacrylicacid ester resins, vinyl alcohol resins, and ethyl vinyl ethers, as wellas polyvinyl butyral resins, polyvinyl formal resins, partly-modifiedpolyvinyl acetals, polycarbonate resins, polyester resins, polyarylateresins, polyamide resins, polyurethane resins, cellulose ester resins,phenoxy resins, silicone resins, silicone-alkyd resins,poly-N-vinylcarbazole resin, and the like. These binder resins may bemodified with a silicon reagent. Among the above binder resins,polycarbonate resins and polyarylate resins are particularly preferred.

Among the polycarbonate resins and polyarylate resins, polycarbonateresins and polyarylate resins containing a bisphenol residue and/or abiphenol residue represented by the following structural formulae arepreferred in view of sensitivity and residual potential. Particularly,polycarbonate resins are more preferred in view of mobility.

In this connection, these binder resin can be used after crosslinked byheat, light, or the like using an appropriate curing agent.

Moreover, any one of the binder resins may be used singly or two or morethereof may be used as a mixture at any combination and in any ratio.

Charge Transport Substance:

The charge transport substance is not particularly limited so long as itis a known substance. There may be, for example, mentionedelectron-withdrawing substances including aromatic nitro compounds suchas 2,4,7-trinitrofluorenone, cyano compounds such astetracyanoquinodimethane, and quinone compounds such as diphenoquinone;electron-donating substances including heterocyclic compounds such ascarbazole derivatives, indole derivatives, imidazole derivatives,oxazole derivatives, pyrazole derivatives, thiadiazole derivatives, andbenzofuran derivatives, as well as aniline derivatives, hydrazonederivatives, aromatic amine derivatives, stilbene derivatives, butadienederivatives, and enamine derivatives, in addition to the compounds inwhich two or more of these compounds are linked with each other andpolymers whose main chain or side chain has one or more of thesecompounds; and the like. Of these, preferred are carbazole derivatives,aromatic amine derivatives, stilbene derivatives, butadiene derivatives,and enamine derivatives, as well as the compounds in which two or moreof these compounds are linked with each other.

Mixing Ratio:

The ratio of the charge transport substance to the binder resin is,relative to 100 parts by weight of the binder resin, usually 20 parts byweight or more, preferably 30 parts by weight or more in the viewpointof reducing residual potential, more preferably 40 parts by weight ormore in view of stability during repetitive use and charge mobility. Onthe other hand, the ratio is usually 150 parts by weight or less in theviewpoint of the thermal stability of the photosensitive layer,preferably 120 parts by weight or less in view of compatibility betweenthe charge transport substance and the binder resin, more preferably 100parts by weight or less in view of print resistance, especiallypreferably 80 parts by weight or less in view of abrasion resistance.

Solvent or Dispersion Medium and Procedure for Dispersion:

The kind of the solvent or dispersion medium and a procedure fordispersing the charge transport substance in the solvent or dispersionmedium are as explained in the article of <Charge generation Layer ofMultilayer Photosensitive Layer>.

Film Thickness:

The film thickness of the charge transport layer is not particularlylimited, but is in the range of usually 5 μm or more, preferably 10 μmor more, and usually 50 μm or less, preferably 45 μm or less, stillpreferably 30 μm or less in view of long-life and image stability aswell as high resolution.

(Single-Layer Photosensitive Layer)

The single-layer photosensitive layer is formed by applying a coatingsolution, which has been obtained by dissolving or dispersing the chargegeneration substance, the charge transport substance, and a binder resinin a solvent, onto the electroconductive substrate (when an undercoatlayer is formed, onto the undercoat layer) and subjected to drying tobind the fine particles of the charge generation substance and thecharge transport substance with the binder resin. As the chargegeneration substance, those explained in the above article of <ChargeGeneration Layer of Multilayer Photosensitive Layer> can be used and, asthe charge transport substance and the binder resin, those explained inthe above article of <Charge Transport Layer of MultilayerPhotosensitive Layer> can be used. The ratio of the charge generationsubstance and the charge transport substance to the binder resin is alsoas explained in the above article of <Charge Generation Layer ofMultilayer Photosensitive Layer> and <Charge Transport Layer ofMultilayer Photosensitive Layer>, respectively.

When the amount of the phthalocyanine crystal dispersed in thesingle-layer photosensitive layer is too small, a sufficient sensitivityis not obtained, while when the amount is too large, there arisedisadvantages such as deterioration in charging property and decline insensitivity. Therefore, for example, the ratio of the charge generationsubstance to 100 parts by weight of the binder resin is in the range ofpreferably 0.1% by weight or more, more preferably 1% by weight or moreand preferably 50% by weight or less, more preferably 20% by weight orless.

The kind of the solvent or dispersion medium and a procedure fordispersing the charge transport substance in the solvent or dispersionmedium are as explained in the article of <Charge generation Layer ofMultilayer Photosensitive Layer>.

The film thickness of the single-layer photosensitive layer is in therange of usually 5 μm or more, preferably 10 μm or more and usually 100μm or less, preferably 50 μm or less.

(Other Components)

In this connection, the photosensitive layer may contain additives suchas well-known antioxidants, plasticizers, ultraviolet absorbers,electron-withdrawing compounds, leveling agents, and visible-lightshielding agents for the purpose of improving film-forming ability,flexibility, coatability, stain resistance, gas resistance, lightresistance, and the like.

[II-4. Other Layers]

As the constitution of the electrophotographic photoreceptor, inaddition to individual layers explained above, the other layers may beformed unless they deviate from the gist of the invention.

For example, it is possible to form a protective layer on thephotosensitive layer for the purposes of protecting the photosensitivelayer against attrition and preventing or lessening degradation of thephotosensitive layer due to causes such as electric discharge productsgenerated from the charging device. The protective layer is formed byincorporating the electroconductive material into an appropriate binderresin or it is also possible to adopt copolymers using compounds havingcharge transport ability, such as triphenylamine skeletons described inJP-A-9-190004. As the electroconductive material, it is possible to usearomatic amino compounds such as TPD(N,N′-diphenyl-N,N′-bis-(m-tolyl)benzidine); metal oxides such asantimony oxide, indium oxide, tin oxide, titanium oxide, tinoxide-antimony oxide, aluminum oxide, and zinc oxide; and the like,although the usable compounds are not limited thereto. As the binderresin used for the protective layer, there can be used known resins suchas polyamide resins, polyurethane resins, polyester resins, epoxyresins, polyketone resins, polycarbonate resins, polyvinyl ketoneresins, polystyrene resins, polyacrylamide resins, siloxane resins, aswell as copolymers containing skeletons having charge transport ability,such as triphenylamine skeletons described in JP-A-9-190004, and theaforementioned resins. The protective layer is constituted preferably soas to have an electric resistance of 10⁹ to 10¹⁴ Ω·cm. When the electricresistance is too high, residual potential may rise and bring about alot of fogging on images, while when the electric resistance is too low,blurring of images and reduction in resolution of images tends to occur.Moreover, the protective layer must be formed in such a manner as not tosubstantially prevent incident light from passing therethrough duringimage exposure.

For the purpose of reducing friction resistance and preventing abrasionof the surface of the electrophotographic photoreceptor as well asimproving transfer efficiency of toner from the electrophotographicphotoreceptor to a transfer belt or a paper form, the surface layer(photosensitive layer, protective layer, or the like) of theelectrophotographic photoreceptor may contain a fluorine resin, asilicone resin, polyethylene resin, or the like. Moreover, the particlesof these resins and the particles of inorganic compounds may becontained.

[II-5. Method of Forming Individual Layers]

These individual layers constituting the photoreceptor is formed bysequentially applying the coating solutions obtained by the abovemethods, through repetition of the application and drying processes, foreach of the layers, on the substrate using known coating methods.

In the case of forming the photosensitive layer of the single-layerphotoreceptor and the charge transport layer of the multilayerphotoreceptor, the solid content of the coating solution is preferablyin the range of usually 5% by weight or more, particularly 10% by weightor more and usually 40% by weight or less, particularly 35% by weight orless. Moreover, the viscosity of the coating solution is preferably inthe range of usually 10 mPa·s or higher, preferably 50 mPa·s or higherand usually 500 mPa·s or lower, preferably 400 mPa·s or lower.

In the case of forming the charge generation layer of the multilayerphotoreceptor, the solid content of the coating solution is preferablyin the range of usually 0.1% by weight or more, particularly 1% byweight or more and usually 15% by weight or less, particularly 10% byweight or less. Moreover, the viscosity of the coating solution ispreferably in the range of usually 0.01 mPa·s or more, particularly 0.1mPa·s or more and usually 20 mPa·s or less, particularly 10 mPa·s orless.

The application methods of the coating solution may include a dipcoating method, a spray coating method, a spinner coating method, a beadcoating method, a wire-bar coating method, a blade coating method, aroller coating method, an air knife coating method, a curtain coatingmethod, and the like. Also, it is possible to use any other knowncoating methods.

The drying process of the coating solution is not particularly limitedbut the coating solution is preferably first dried to touch at roomtemperature and then heat-dried under a still or ventilated condition.Heating temperature may be in a temperature range of particularly 30 to200° C. for 1 minute to two hours and may be either kept constant orvaried during the drying process.

[III. Image-Forming Device]

Next, explanation will be given of an embodiment of the image-formingdevice using the electrophotographic photoreceptor of the invention(image-forming device of the invention) with reference to FIG. 1, whichshows the constitution of the substantial part of the device. However,the embodiments of the examples are not limited to the followingexplanation, and can be implemented with arbitrary modification unlessthey deviate from the gist of the invention.

As shown in FIG. 1, the image-forming device is constituted by anelectrophotographic photoreceptor 1, a charging device 2, an exposingdevice 3, and a developing device 4, with optionally provided asnecessary, a transfer device 5, a cleaning device 6, and a fixing device7.

The electrophotographic photoreceptor 1 is not particularly limited aslong as the aforementioned electrophotographic photoreceptor of theinvention is used and FIG. 1 indicates, as an example, a drum-shapedphotoreceptor in which the aforementioned photosensitive layer is formedon the cylindrical surface of the electroconductive substrate. Along thecircumferential surface of the electrophotographic photoreceptor 1 aredisposed a charging device 2, an exposing device 3, a developing device4, a transfer device 5, and a cleaning device 6, respectively.

The charging device 2 is intended to electrically charge theelectrophotographic photoreceptor 1 and capable of electrically chargingthe surface of the electrophotographic photoreceptor 1 uniformly to apredetermined electric potential. As the charging device, there may befrequently used corona charging devices such as corotrons andscorotrons; direct charging devices wherein a direct charging member towhich a voltage is applied is then brought into contact with thephotoreceptor's surface so as to carry out electrical charging(contact-type charging device); contact-type charging devices such ascharging brushes; and the like. Examples of the direct electricalcharging means include contact charging devices such as charging rollersand charging brushes. As an example of the electrical charging device 2,FIG. 1 indicates a roller-type charging device (charging roller). As thedirect electrical charging means, it is possible to carry out eithercharging that involves aerial electric discharge or injection chargingthat does not involve aerial electric discharge. As the voltage appliedduring charging, there may be used either a direct current alone or asuperimposed current in which an alternating current is superimposed ona direct current.

There is no particular limitation on the type of the exposing device 3so long as it can carry out exposure of the electrophotographicphotoreceptor 1 to thereby form an electrostatic latent image on thephotosensitive surface of the electrophotographic photoreceptor 1.Specific examples include halogen lamps, fluorescent lamps, lasers suchas semiconductor laser and He—Ne laser, LED, and the like. It is alsopossible to carry out exposure of the photoreceptor using an exposingmethod from inside the photoreceptor. The light used for the exposuremay be selected arbitrarily and, for example, the exposure may becarried out with monochromatic light having a wavelength of about 780nm, monochromatic light having slightly shorter wavelengths of about 600nm to 700 nm, and monochromatic light having short wavelengths of about380 nm to 500 nm.

The developing device 4 is not particularly limited in its type, and anyknown device using either dry development method, such as cascadedevelopment, mono-component insulating toner development, mono-componentconductive toner development, and two-component magnetic brushdevelopment or wet process development method can be employed. FIG. 1shows a constitution in which the developing device 4 comprises adeveloping bath 41, agitators 42, a feeding roller 43, a developingroller 44, and a regulating member 45, and toner T is stored in thedeveloping bath 41. In addition, the developing device 4 may beprovided, as necessary, with a supplying device (not shown in thefigure) for supplying the toner T. The supplying device is constitutedin such a manner as to be capable of supplying the toner T from areceptacle such as a bottle or a cartridge.

The feeding roller 43 is composed of an electroconductive sponge or thelike. The developing roller 44 may be formed as a metal roll made ofiron, stainless steel, aluminum, nickel, etc.; a resin roll in whichsuch a metal roll is coated with a resin such as a silicone resin, aurethane resin, or a fluorine resin; or the like. If necessary, thesurface of the developing roller 44 may undergo smoothing processing orroughening processing.

The developing roller 44 is disposed between the electrophotographicphotoreceptor 1 and the feeding roller 43 and is in direct contact witheach of the electrophotographic photoreceptor 1 and the feeding roller43. The feeding roller 43 and the developing roller 44 are each rotatedby a rotation drive mechanism (not shown in the figure). The feedingroller 43 carries the stored toner T and provides it to the developingroller 44. The developing roller 44 carries the toner T provided by thefeeding roller 43 and brings it into contact with the surface of theelectrophotographic photoreceptor 1.

The regulating member 45 may be formed as a resin blade made of asilicone resin, a urethane resin, or the like; a metal blade made ofstainless steel, aluminum, copper, brass, phosphor bronze, or the like;a blade in which such a metal blade is resin-coated; or the like. Theregulating member 45 is in direct contact with the developing roller 44and pressed onto the developing roller 44 under a predetermined force(normal blade linear load is from 5 to 500 g/cm) by means of a spring orthe like. If necessary, the regulating member 45 may also be equippedwith the function of charging the toner T by means of frictionalcharging with the toner T.

The agitators 42 are each rotated by a rotation drive mechanism so as toagitate the toner T and transfer the toner T toward the feeding roller43. There may also be provided plural agitators 42 whose blades aredifferent with each other in their shapes, sizes, etc.

As the toner, it is possible to use not only pulverized toner but alsochemical toner obtained by suspension granulation, suspensionpolymerization, emulsion polymerization agglomeration process, or thelike. Particularly, in the case of the chemical toner, a toner having asmall particle size of about 4 to 8 μm is used, and it may have anyshape from a substantially spherical shape to a shape deviating fromspherical such as a potato shape or a rugby ball. The polymerized toneris superior in charging uniformity and transferring ability and hencesuitable for enhancing image quality.

The kind of the toner T is not limited and it is possible to use notonly powdery toner but also chemical toner obtained by suspensiongranulation, suspension polymerization, emulsion polymerizationagglomeration process, or the like. In the case of the chemical toner, atoner having a small particle size of about 4 to 8 μm is used, and itmay have any shape from a substantially spherical shape to a shapedeviating from spherical such as a potato shape or a rugby ball. Inparticular, the polymerized toner is superior in charging uniformity andtransferring ability and hence suitable for enhancing image quality.

With regard to the shape of the toner to be used in the image-formingdevice of the invention, the average circularity measured by a flow typeparticle image analyzer is preferably 0.940 or more, more preferably0.950 or more, further preferably 0.960 or more. When the shape of thetoner is nearer to spherical form, localization of the charging withinthe toner particle hardly occurs, so that a developing property tends tobe homogeneous. Moreover, an upper limit of the above averagecircularity is not limited so long as it is 1.000 or less. However, whenthe shape of the toner approaches a spherical form, insufficientcleaning is apt to occur and it is difficult to produce a completelyspherical toner, so that the value is preferably 0.995 or less, morepreferably 0.990 or less.

In this connection, the above average circularity is used as aconvenient way to express the shape of the toner particlequantitatively. In the invention, measurement is carried out using aflow type particle image analyzer FPIA-2000 manufactured by SysmexCorp., and the circularity [a] of the particle measured is determinedfrom the following equation (A):Circularity a=L ₀ /L  (A)wherein L₀ represents circumference length of the circle having aprojection area the same as that of a particle image and L representscircumference length of the particle image subjected to image treatment.

The above circularity is a measure of degree of unevenness of the tonerparticle. The circularity is 1.00 in the case where the toner iscompletely spherical and the value decreases as the surface shape iscomplicated.

A specific method for measuring the average circularity is as follows.Namely, a surfactant (preferably an alkylbenzenesulfonate salt) as adispersant is added into 20 mL of water from which impurities in avessel are removed in advance, followed by addition of about 0.05 g of asample to be measured (toner). The suspension containing the sampledispersed therein is irradiated with ultrasonic wave for 30 seconds toachieve a dispersion concentration of 3.0 to 8.0×10004/μL andcircularity distribution of the particles having a circle-correspondingdiameter having 0.60 μm to less than 160 μm is measured.

Various kinds of the toners may be usually obtained depending on theproduction process but any one can be used as the toner to be used inthe image-forming device of the invention.

The kinds of toner and the kinds of the production process of the tonerare explained below.

The toner of the invention may be produced by any conventionally knownprocesses and, for example, a polymerization process, a melt suspensionprocess, and the like are mentioned but preferred is a so-calledpolymerized toner wherein the toner is formed in an aqueous medium. Asthe polymerized toner, a suspension polymerized toner, an emulsionpolymerization agglomeration process toner, and the like may bementioned, for example. In particular, the emulsion polymerizationagglomeration process is a process wherein a toner is produced byagglomerating polymer resin fine particles, colorant, and the like in aliquid medium and the particle size and circularity of the toner can beregulated by controlling agglomeration conditions, so that the processis preferred.

Moreover, in order to improve releasing ability, low-temperature fixingability, high-temperature offset property, filming resistance, etc. ofthe toner, a method of incorporating a low-softening-point substance(so-called wax) into the toner has been proposed. In the melt kneadingpulverizing method, it is difficult to increase the amount of waxcontained in the toner and about 5% by weight relative to the polymer(binder resin) is regarded as a limit. Contrarily, in the polymerizedtoner, as described in JP-A-5-88409 and JP-A-11-143125, it is possibleto contain the low-softening-point substance in a large amount (5 to 30%by weight). In this connection, the polymer herein is one of thematerials constituting the toner and, for example, is obtained bypolymerizing a polymerizable monomer in the case of the toner to beproduced by the emulsion polymerization agglomeration process to bementioned below.

[Toner to be Produced by Emulsion Polymerization Agglomeration Process]

The following will describe further in detail the toner to be producedby the emulsion polymerization agglomeration process.

In the case of producing the toner by the emulsion polymerizationagglomeration process, as production steps thereof, a polymerizationstep, a mixing step, an agglomeration step, a fusion step, and awashing/drying step are usually carried out. Namely, in general, polymerprimary particles are obtained by emulsion polymerization(polymerization step), materials to be dispersed, such as a colorant(pigment), wax, and a charge-regulating agent are mixed according toneed (mixing step), an agglomerating agent id added to the dispersionliquid to agglomerate the primary particles into a particle agglomerate(agglomeration step), an operation for attaching fine particles or thelike is carried out according to need and subsequently fusion is carriedout to obtain particles (fusion step), and the resulting particles arewashed and dried (washing/drying step), thereby mother particles beingobtained.

1. Polymerization Step

The fine particles of the polymer (polymer primary particles) are notparticularly limited. Therefore, any of fine particles obtained bypolymerizing polymerizable monomer(s) by a suspension polymerizationprocess, an emulsion polymerization process, or the like and fineparticles obtained by pulverizing a lump of a polymer such as a resinmay be used as the polymer primary particles. However, those obtained bya polymerization process, particularly an emulsion polymerizationprocess, specifically an emulsion polymerization process using wax as aseed are preferred. When wax is used as a seed in the emulsionpolymerization process, there is obtained fine particles where wax iswrapped with the polymer as the polymer primary particles. According tothe process, the wax can be contained in the toner without exposing thewax on the toner surface. Therefore, the device members is not stainedby the wax, the charging property of the toner is not impaired, andlow-temperature fixing property and high-temperature offset property,filming resistance, release property, and the like can be improved.

The following will describe a method wherein emulsion polymerization iscarried out using wax as a seed to thereby obtain primary particles of apolymer.

The emulsion polymerization may be carried out according to the hithertoknown method. Usually, wax is dispersed in a liquid medium in thepresence of an emulsifier to form wax fine particles, to which apolymerization initiator, a polymerizable monomer which gives a polymerby polymerization, i.e., a compound having a polymerizable carbon-carbondouble bond, and, if necessary, a chain transfer agent, a pH regulator,a polymerization degree controlling agent, a defoaming agent, aprotective colloid, an internal additive, and the like are added,followed by stirring to effect polymerization. Thereby, there isobtained an emulsion in which polymer fine particles having a structurewhere wax is wrapped with the polymer (i.e., polymer primary particles)are dispersed in the liquid medium. As the structure where wax iswrapped with the polymer, core-shell type, phase separation type,occlusion type, and the like are mentioned but the core-shell type ispreferred.

(i. Wax)

As the wax, any one known to be usable in this application can be used.Examples include olefin-based waxes such as low-molecular-weightpolyethylene, low-molecular-weight polypropylene, and copolymerpolyolefins; paraffin waxes; silicone waxes having an alkyl group;fluorinated resin-based waxes such as low-molecular-weightpolytetrafluoroethylene; higher aliphatic acids such as stearic acid;long chain aliphatic alcohols such as eicosanol; ester-based waxeshaving a long-chain aliphatic group, such as behenyl behenate, montanateesters, and stearyl stearate; ketones having a long-chain alkyl groupsuch a as distearyl ketone; vegetable waxes such as hydrogenated casteroil and carnauba wax; esters or partial esters obtained from apolyhydric alcohol such as glycerin or pentaerythritol and a long-chainfatty acid; higher aliphatic acid amides such as oleamide andstearamide; low-molecular weight polyesters; and the like. Among these,preferred are those having at least one exothermic peak by differentialscanning calorimetry (DSC) at 50 to 100° C.

Among the waxes, for example, the ester-based waxes, paraffin waxes,olefin-based waxes such as low-molecular-weight polypropylene andcopolymer polyethylene, silicone waxes, and the like are preferred sincea releasing effect is obtained in a small amount. Particularly, paraffinwaxes are preferred.

Waxes may be used singly or two or more thereof may be used incombination at any combination and in any ratio.

In the case of using the wax, the amount is arbitrary. However, it isdesirable to use the wax in an amount of usually 3 parts by weight ormore, preferably 5 parts by weight or more and usually 40 parts byweight or less, preferably 30 parts by weight or less relative to 100parts by weight of the polymer. When the amount of the wax is too small,there is a possibility that a fixing temperature range is insufficient,while when the amount is too large, there is a risk that device membersare stained to deteriorate image quality.

(ii. Emulsifier)

There is no limitation on the emulsifier and anyone can be used withinthe range where the advantages of the invention are not remarkablyimpaired. For example, any of nonionic, anionic, cationic, andamphoteric surfactants can be used.

Examples of the nonionic surfactant include polyoxyalkylene alkyl etherssuch as polyoxyethylene lauryl ether; polyoxyalkylene alkylphenyl ethersuch as polyoxyethylene octylphenyl ether; sorbitan fatty acid esterssuch as sorbitan monolaurate; and the like.

Moreover, examples of the anionic surfactant include fatty acid saltssuch as sodium stearate and sodium oleate; alkylarylsulfonates saltssuch as sodium dodecylbenzenesulfonate; alkyl sulfate esters such assodium lauryl sulfate; and the like.

Furthermore, examples of the cationic surfactant include alkylaminesalts such as laurylamine acetate; quaternary ammonium salts such aslauryltrimethylammonium chloride; and the like.

Additionally, examples of the amphoteric surfactant include alkylbetaines such as lauryl betaine, and the like.

Of these, nonionic surfactants and anionic surfactants are preferred.

The emulsifier may be used singly or two or more thereof may be used incombination at any combination and in any ratio.

Furthermore, the mixing amount of the emulsifier is arbitrary so long asthe advantages of the invention are not remarkably impaired but theemulsifier is used in a ratio of usually 1 to 10 parts by weightrelative to 100 parts by weight of the polymerizable monomer.

(iii. Liquid Medium)

As the liquid medium, an aqueous medium is usually used and particularlypreferably, water is used. However, the quality of the liquid mediumrelates to coarse particle formation by re-agglomeration of theparticles in the liquid medium and when conductivity of the liquidmedium is high, dispersion stability with time tends to be deteriorated.Therefore, in the case where an aqueous medium such as water is used asthe liquid medium, it is preferred to use ion-exchange water ordistilled water subjected to demineralization treatment so that theconductivity becomes usually 10 μS/cm or less, preferably 5 μS/cm orless. In this connection, the measurement of the conductivity isconducted at 25° C. using a conductivity meter (a personal SC meterModel SC72 and a detector SC72SN-11 manufactured by Yokogawa ElectricCorporation).

Moreover, there is no limitation on the amount of the liquid medium tobe used but it is usually used in an amount of about 1 to 20 weightequivalents by weight of the polymerizable monomer(s).

The liquid medium may be used singly or two or more thereof may be usedin combination at any combination and in any ratio.

By dispersing the above wax into the liquid medium in the presence of anemulsifier, wax fine particles are obtained. Although the order ofmixing the emulsifier and wax with the liquid medium is arbitrary,usually, the emulsifier is first mixed with the liquid medium and thenwax is mixed therewith. Moreover, the emulsifier may be continuouslymixed with the liquid medium.

(iv. Polymerization Initiator)

After the above wax fine particles are prepared, a polymerizationinitiator is mixed with the liquid medium. As the polymerizationinitiator, anyone may be used so far as the advantages of the inventionare not remarkably impaired. Examples thereof include persulfate saltssuch as sodium persulfate and ammonium persulfate; organic peroxidessuch as t-butyl hydroperoxide, cumene hydroperoxide, and p-menthanehydroperoxide; inorganic peroxides such as hydrogen peroxide; and thelike. Of these, inorganic peroxides are preferred. The polymerizationinitiator may be used singly or two or more thereof may be used incombination at any combination and in any ratio.

Furthermore, as the other examples of the polymerization initiator, apersulfate salt, an organic or inorganic peroxide and a reductiveorganic compound such as ascorbic acid, tartaric acid, or citric acid, areductive inorganic compound such as sodium thiosulfate, sodiumbisulfate, or sodium metabisulfate are used in combination to form aredox initiator. In this case, the reductive inorganic compound may beused singly or two or more thereof may be used in combination at anycombination and in any ratio.

Moreover, there is no limitation on the amount of the polymerizationinitiator to be used but it is usually used in an amount of 0.05 to 2parts by weight relative to 100 parts by weight of the polymerizablemonomer(s).

(v. Polymerizable Monomer)

After the above wax fine particles are prepared, the liquid medium ismixed with polymerizable monomer(s) in addition to the polymerizationinitiator. There is no limitation on the polymerizable monomer(s) but,for example, monofunctional monomers such as styrenes, (meth)acrylateesters, acrylamides, monomers having a Brønsted acid group (hereinaftersometimes simply abbreviated as “acidic monomer”), and monomers having aBrønsted basic group (hereinafter sometimes simply abbreviated as “basicmonomer”) are mainly used. Moreover, a monofunctional monomer can beused in combination with a polyfunctional monomer.

Examples of the styrenes include styrene, methylstyrene, chlorostyrene,dichlorostyrene, p-tert-butylstyrene, p-n-butylstyrene,p-n-nonylstyrene, and the like.

Moreover, examples of the (meth)acrylate esters include methyl acrylate,ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate,hydroxyethyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethylmethacrylate, propyl methacrylate, n-butyl methacrylate, isobutylmethacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, andthe like.

Examples of the acrylamides include acrylamide, N-propylacrylamide,N,N-dimethylacrylamide, N,N-dipropylacrylamide, N,N-dibutylacrylamide,and the like.

Furthermore, examples of the acidic monomer include monomers having acarboxyl group, such as acrylic acid, methacrylic acid, maleic acid,fumalic acid, and cinnamic acid; monomers having a sulfonic acid group,such as sulfonated styrene; monomers having a sulfonamido group, such asvinylbenzenesulfonamide; and the like.

Moreover, examples of the basic monomer include aromatic vinyl compoundshaving an amino group, such as aminostyrene; monomers containing annitrogen-containing heterocycle, such as vinylpyridine andvinylpyrrolidone; (meth)acrylate esters having an amino group, such asdimethylaminoethyl acrylate and diethylaminoethyl methacrylate; and thelike.

The acidic monomers and basic monomers may be present as salts withcounter ions.

Furthermore, examples of the polyfunctional monomers includedivinylbenzene, hexanediol diacrylate, ethylene glycol dimethacrylate,diethylene glycol dimethacrylate, diethylene glycol diacrylate,triethylene glycol diacrylate, neopentyl glycol dimethacrylate,neopentyl glycol diacrylate, diallyl phthalate, and the like.Additionally, it is also possible to use monomers having a reactivegroup, such as glycidyl methacrylate, N-methylol acrylamide, andacrolein. Of these, radically polymerizable difunctional monomers,particularly divinlbenzene and hexanediol diacrylate are preferred.

Of these, the polymerizable monomer is preferably composed of at least astyrene, a (meth)acrylate ester, and/or an acidic monomer having acarboxyl group. Particularly, styrene is preferred as the styrene, butylacrylate is preferred as the (meth)acrylate ester, and acrylic acid ispreferred as the acidic monomer having a carboxyl group.

The polymerizable monomer may be used singly or two or more thereof maybe used in combination at any combination and in any ratio.

At the time when emulsion polymerization is carried out using wax as aseed, the acidic monomer or the basic monomer is preferably used incombination with a monomer other than these monomers. This is becausethe dispersion stability of the polymer primary particles can beimproved by combined use of the acidic monomer or the basic monomer.

On this occasion, the mixing amount of the acidic monomer or the basicmonomer is arbitrary but it is desirable that the amount of the acidicmonomer or the basic monomer to be used relative to 100 parts by weightof the total polymerizable monomer(s) is usually 0.05 part by weight ormore, preferably 0.5 part by weight or more, more preferably 1 part byweight or more and usually 10 parts by weight or less, preferably 5parts by weight or less. When the mixing amount of the acidic monomer orthe basic monomer is less than the above range, there is a possibilitythat the dispersion stability of the polymer primary particles may bedeteriorated, while when the amount exceeds the upper limit, there is apossibility that the charging property of the toner may be adverselyinfluenced.

Moreover, in the case of the polyfunctional monomer is used incombination, the mixing amount is arbitrary but it is desirable that theamount of the polyfunctional monomer to be used relative to 100 parts byweight of the total polymerizable monomer(s) is usually 0.005 part byweight or more, preferably 0.1 part by weight or more, more preferably0.3 part by weight or more and usually 5 parts by weight or less,preferably 3 parts by weight or less, more preferably 1 part by weightor less. By using the polyfunctional monomer, the fixing property of thetoner can be improved. When the mixing amount of the polyfunctionalmonomer is less than the above range, there is a possibility that thehigh-temperature offset property may be poor, while when the amountexceeds the upper limit, there is a possibility that the low-temperaturefixing property may be poor.

The method for mixing the polymerizable monomer with the liquid mediumis not particularly limited. For example, any of addition at once,continuous addition, and intermittent addition may be used but, in viewof reaction control, continuous mixing is preferred. Moreover, in thecase where two or more polymerizable monomers are used in combination,individual polymerizable monomers may be separately mixed or may bemixed with the liquid medium after they have been blended beforehand.Furthermore, they may be mixed with changing the composition of themonomer mixture.

(vi. Chain Transfer Agent, etc.)

After the above wax fine particles are prepared, if necessary, additivessuch as a chain transfer agent, a pH regulator, a polymerization degreecontrolling agent, a defoaming agent, a protective colloid, and aninternal additive are mixed with the liquid medium in addition to thepolymerization initiator and the polymerizable monomer(s). Theseadditives are arbitrary used so long as the advantages of the inventionare not remarkably impaired. These additives may be used singly or twoor more thereof may be used in combination at any combination and in anyratio.

As the chain transfer agent, any known one can be used. Specificexamples include t-dodecylmercaptan, 2-mercaptoethanol,diisopropylxanthogen, carbon tetrachloride, trichlorobromoethane, andthe like. Moreover, the chain transfer agent is used in a ratio ofusually 5 parts by weight or less relative to 100 parts by weight of thepolymerizable monomer(s).

Furthermore, as the protective colloid, anyone known to be usable inthis application can be used. Specific examples include polyvinylalcohols such as partially or completely saponified polyvinyl alcohols,cellulose derivatives such as hydroxyethyl cellulose, and the like.

Moreover, as the internal additive, there may be, for example, mentionedthose for modifying pressure-sensitive adhesiveness, agglomerationability, fluidity, charging property, surface resistance, and the likeof the toner, such as silicone oil, silicone varnish, and fluorinatedoil.

(Vii. Polymer Primary Particles)

The polymer primary particles are obtained by mixing the liquid mediumcontaining wax fine particles with the polymerization initiator and thepolymerizable monomer(s) and, if necessary, additives, followed bystirring to effect polymerization. The polymer primary particles can beobtained in an emulsion state in the liquid medium.

The order of mixing the polymerization initiator, the polymerizablemonomer(s), additives, and the like with the liquid medium is notlimited. Also, the methods of mixing and stirring are not limited andarbitrary.

Furthermore, the reaction temperature of the polymerization (emulsionpolymerization reaction) is also arbitrary so long as the reactionproceeds. However, the polymerization temperature is usually 50° C. orhigher, preferably 60° C. or higher, more preferably 70° C. or higherand usually 120° C. or lower, preferably 100° C. or lower, morepreferably 90° C. or lower.

There is no limitation on the volume average particle size of thepolymer primary particles but is usually 0.02 μm or more, preferably0.05 μm or more, more preferably 0.1 μm or more and usually 3 μm orless, preferably 2 μm or less, more preferably 1 μm or less. When thevolume average particle size is too small, the control of theagglomeration speed is sometimes difficult, while when the volumeaverage particle size is too large, the particle size of the tonerobtained by agglomeration tends to be large and it is sometimesdifficult to obtain a toner having an objective particle size. Thevolume average particle size can be measured by means of a particle sizeanalyzer using the dynamic light scattering method to be mentionedbelow.

In the invention, the volume average particle size is measured by thedynamic light scattering method. This methodology determines particlesize by detecting, through irradiation of the particles with a laserlight, scattering (Doppler shift) of lights having different phasesdepending on the speed of Brownian motion of the particles finelydispersed. In actual measurement, with regard to the above volumeparticle size, the measurement is conducted under the followingconditions using an ultrafine particle size distribution measuringapparatus (manufactured by Nikkiso Co., Ltd., UPA-EX150, hereinafterabbreviated as UPA).

Upper limit in measurement: 6.54 μm

Lower limit in measurement: 0.0008 μm

Number of channels: 52

Time for measurement: 100 sec.

Particle transparency: absorption

Particle diffractive index: N/A (not applied)

Particle shape: non-spherical

Density: 1 g/cm³

Kind of dispersion medium: WATER

Diffractive index of dispersion medium: 1.333

At the measurement, the dispersion of the particles is diluted with aliquid medium so that the concentration index of the sample falls withinthe range of 0.01 to 0.1 and a sample subjected to dispersion treatmentin an ultrasonic washer is measured. The volume average particle size ismeasured as an arithmetic average value of the results of the abovevolume particle size distribution.

The polymer constituting the polymer primary particles desirably has atleast one of the peak molecular weights in gel permeation chromatography(hereinafter optionally abbreviated as “GPC”) of usually 3,000 or more,preferably 10,000 or more, more preferably 30,000 or more and usually100,000 or less, preferably 70,000 or less, more preferably 60,000 orless. When the peak molecular weight is present within the above range,durability, storability, and fixing ability of the toner tend to begood. As the above peak molecular weight, a value in terms ofpolystyrene is used and, at the measurement, a solvent-insolubleingredient is removed. It is possible to measure the peak molecularweight in the same manner as in the case of the toner to be mentionedbelow.

Particularly, in the case where the above polymer is a styrene-basedresin, the number-average molecular weight of the polymer in gelpermeation chromatography is usually 2,000 or more, preferably 2,500 ormore, more preferably 3,000 or more as the lower limit and usually50,000 or less, preferably 40,000 or less, more preferably 35,000 orless as the upper limit. Furthermore, the weight-average molecularweight of the polymer is usually 20,000 or more, preferably 30,000 ormore, more preferably 50,000 or more as the lower limit and usually1,000,000 or less, preferably 500,000 or less as the upper limit. Thisis because the resulting toner has good durability, storability, fixingability in the case where there is used, as the polymer, a styrene-basedresin wherein at least one of the number-average molecular weight andthe weight-average molecular weight, preferably both of them fall withinthe above ranges. Furthermore, in the molecular weight distribution,those having two main peaks may be used. The styrene-based resin refersto a polymer wherein styrenes are contained in a ratio of usually 50% byweight or more, preferably 65% by weight or more in the whole polymer.

Moreover, the softening point of the polymer (hereinafter, sometimes,referred to as “Sp”) is usually 150° C. or lower, preferably 140° C. orlower in view of low-energy fixing and usually 80° C. or higher,preferably 100° C. or higher in view of high-temperature offsetresistance and durability. The softening point of the polymer can bedetermined as a temperature at a middle point of a strand from the startand finish of flow when 1.0 g of a sample is measured under conditionsof a nozzle of 1 mm×10 mm, a load of 30 kg, a preheating time of 5minutes at 50° C., and a temperature-elevating rate of 3° C./minute in aflow tester.

Furthermore, the glass transition temperature [Tg] of the polymer isusually 80° C. or lower, preferably 70° C. or lower. When the glasstransition temperature [Tg] of the polymer is too high, there is apossibility that low-energy fixing may not be achieved. Moreover, thelower limit of the glass transition temperature [Tg] of the polymer isusually 40° C. or higher, preferably 50° C. or higher. When the glasstransition temperature [Tg] of the polymer is too low, there is a riskthat blocking resistance may be lowered. The glass transitiontemperature [Tg] of the polymer can be determined as a temperature at acrossing point of two tangent lines when the tangent lines are drawn attransition (inflection) start points of a curve measured under atemperature-elevating rate of 10° C./minute in a differential scanningcalorimeter.

The softening point and the glass transition temperature [Tg] of thepolymer can be adjusted to the above range by controlling the kind,monomer composition ratio, molecular weight, etc. of the polymer.

2. Mixing Step and Agglomeration Step

An emulsion of agglomerated matter (agglomerated particles) containing apolymer and a pigment is obtained by mixing pigment particles into anemulsion containing the above polymer primary particles dispersedtherein, followed by agglomeration. On this occasion, with regard to thepigment, it is preferred that a pigment particle dispersion where thepigment is homogeneously dispersed in the liquid medium beforehand usinga surfactant or the like is prepared and the dispersion is mixed intothe emulsion of the polymer primary particles. At that time, as theliquid medium for the pigment particle dispersion, an aqueous solventsuch as water is usually used and the pigment particle dispersion isprepared as an aqueous dispersion. Moreover, at that time, wax, acharge-regulating agent, a releasing agent, an internal additive, andthe like may be mixed into the emulsion. Furthermore, in order tomaintain the stability of the pigment particle dispersion, theaforementioned emulsifier may be added.

As the polymer primary particles, the aforementioned polymer primaryparticles obtained by emulsion polymerization can be used. On thisoccasion, the polymer primary particles may be used singly or two ormore thereof may be used in combination at any combination and in anyratio. Furthermore, polymer primary particles (hereinafter optionallyreferred to as “combination-use polymer particles”) produced fromstarting materials and reaction conditions different from the case ofthe aforementioned emulsion polymerization may be used in combination.

As the combination-use polymer particles, for example, fine particlesobtained by suspension polymerization and pulverization may bementioned. As a material for such combination-use polymer particles, aresin can be used. As the resin, in addition to the (co)polymers of themonomers for use in the aforementioned emulsion polymerization, theremay be, for example, mentioned homopolymers and copolymers of vinylicmonomers such as vinyl acetate, vinyl chloride, vinyl alcohol, vinylbutyral, and vinylpyrrolidone; thermoplastic resins such as saturatedpolyester resins, polycarbonate resins, polyamide resins, polyolefinresins, polyarylate resins, polysulfone resins, and polyphenylene etherresins; thermosetting resins such as unsaturated polyester resins,phenol resins, epoxy resins, urethane resins, and rosin-modified maleicacid resins; and the like. These combination-use polymer particles maybe used singly or two or more thereof may be used in combination at anycombination and in any ratio. However, the ratio of the combination-usepolymer particles is usually 5% by weight or less, preferably 4% byweight or less, more preferably 3% by weight or less relative to thetotal of the polymers of the polymer primary particles and thecombination-use polymer particles.

Moreover, there is no limitation on the pigment and anyone may be useddepending on its application. However, the pigment is usually present ina particle form as colorant particles and the particles of the pigmentpreferably have small difference in density from the polymer primaryparticles in the emulsion polymerization agglomeration process. This isbecause small density difference may result in a homogeneousagglomeration state in the case of agglomerating the polymer primaryparticles and the pigment and hence the performance of the resultingtoner is improved. In this connection, the density of the polymerprimary particles is usually from 1.1 to 1.3 g/cm³.

From the aforementioned viewpoint, the true density of the pigmentparticles measured by the picno meter method defined by JIS K5101-11-1:2004 is usually 1.2 g/cm³ or more, preferably 1.3 g/cm³ ormore and usually less than 2.0 g/cm³, preferably 1.9 g/cm³ or less, morepreferably 1.8 g/cm³ or less. In the case where the true density of thepigment is large, the precipitation ability particularly in the liquidmedium tends to become worse. In addition, in consideration of theproblems such as storability and sublimation property, the pigment ispreferably carbon black or an organic pigment.

Examples of the pigment satisfying the above requirements include yellowpigments, magenta pigments, cyan pigments, and the like shown in thefollowing. Moreover, as black pigment, carbon black or a pigment tonedto black by mixing a yellow pigment/magenta pigment/cyan pigment shownin the following is utilized.

Among them, carbon black to be used as a black pigment is present asagglomerated matter of very fine primary particles and, when dispersedas a pigment particle dispersion, coarse particle formation of carbonblack particles by re-agglomeration is apt to occur. The degree of there-agglomeration of the carbon black particles correlates to the amountof impurities (degree of residual undecomposed organic substances)contained in the carbon black and, when the amount of the impurities islarge, coarse particle formation by re-agglomeration after dispersingtends to be remarkable.

With regard to the quantitative evaluation of the amount of theimpurities, the ultraviolet absorbance of the toluene extract of thecarbon black measured by the following measuring method is usually 0.05or less, preferably 0.03 or less. In general, since the carbon blackfrom the channel process tends to contain a large amount of impurities,one produced by the furnace process is preferred as the carbon black tobe used in the invention.

In this connection, the ultraviolet absorbance (λc) of carbon black isdetermined by the following method. Namely, 3 g of carbon black is firstthoroughly dispersed and mixed in 30 mL of toluene and subsequently themixed solution is filtrated using No. 5C filter. Thereafter, thefiltrate is placed in a quartz cell having an absorbing part 1 cm squareand ultraviolet absorbance is determined according to the equation:λc=λs−λo from a value (λs) of absorbance of the filtrate measured atwavelength of 336 nm using a commercially available ultravioletspectrophotometer and a value (λo) of absorbance of toluene alone in thesame manner as a reference. As the commercially availablespectrophotometer, there are an ultraviolet-visible spectrophotometer(UV-3100PC) manufactured by Shimadzu Corporation and the like.

Moreover, as the yellow pigments, for example, compounds includingcondensed azo compounds, isoindolinon compounds, and the like asrepresentatives are used. Specifically, C. I. Pigment Yellow 12, 13, 14,15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180,185, etc. are suitably used.

Furthermore, as the magenta pigments, for example, condensed azocompounds, diketopyrrolopyrrole compounds, anthraquinone, quinacridonecompounds, basic dye lake compounds, naphthol compounds, benzimidazolonecompounds, thioindigo compounds, perylene compounds, and the like areused. Specifically, C. I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3,48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 207,209, 220, 221, 238, 254, C. I. Pigment Violet 19, etc. are suitablyused.

Of these, quinacridone-based pigments represented by C. I. Pigment Red122, 202, 207, 209, C. I. Pigment Violet 19 are particularly preferred.The quinacridone-based pigments are suitable as magenta pigments becauseof vivid hue, high light fastness, and the like. Among thequinacridone-based pigments, the compound represented by C. I. PigmentRed 122 is particularly preferred.

Moreover, as the cyan pigments, for example, copper phthalocyaninecompounds and derivatives thereof, anthraquinone compounds, basic dyelake compounds, and the like can be utilized. Specifically, C. I.Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, 66, etc. areparticularly suitably utilized.

The pigments may be used singly or two or more thereof may be used incombination at any combination and in any ratio.

The above pigment is dispersed into a liquid medium to form a pigmentparticle dispersion and is then mixed with an emulsion containing thepolymer primary particles. On this occasion, the amount of the pigmentparticles to be used in the pigment particle dispersion is usually 3parts by weight or more, preferably 5 parts by weight or more andusually 50 parts by weight or less, preferably 40 parts by weight orless relative to 100 parts by weight of the liquid medium. When themixing amount of the colorant is more than the above range, the pigmentconcentration is thick and hence the probability of re-agglomeration ofthe pigment particles during dispersing increases, so that the case isnot preferred. When the amount is less than the above range, dispersingis excessively promoted and it becomes difficult to obtain a suitableparticle size distribution, so that the case is not preferred.

Moreover, the ratio of the amount of the pigment relative to the polymercontained in the polymer primary particles is usually 1% by weight ormore, preferably 3% by weight or more and usually 20% by weight or less,preferably 15% by weight or less. When the amount of the pigment to beused is too small, there is a possibility that image density decreases,while when the amount is too large, there is a possibility that thecontrol of the agglomeration becomes difficult.

Furthermore, a surfactant may be contained in the pigment particledispersion. The surfactant is not particularly limited but there may be,for example, mentioned those the same as the surfactants exemplified asemulsifiers in the explanation of the emulsion polymerization process.Of these, nonionic surfactants, anionic surfactants includingalkylarylsulfonate salts such as sodium dodecylbenzenesulfonate,polymeric surfactants, and the like are preferably used. Moreover, onthis occasion, the surfactants may be used singly or two or more thereofmay be used in combination at any combination and in any ratio.

The ratio of the pigment in the pigment particle dispersion is usuallyfrom 10 to 50% by weight.

As the liquid medium for the pigment particle dispersion, an aqueousmedium is usually used and particularly preferably, water is used. Onthis occasion, the water quality of the polymer primary particles andpigment particle dispersion relates to coarse particle formation byre-agglomeration of the individual particles in the liquid medium and,when conductivity is high, dispersion stability with time tends to bedeteriorated. Therefore, it is preferred to use ion-exchange water ordistilled water subjected to demineralization treatment so that theconductivity becomes usually 10 μS/cm or less, preferably 5 μS/cm orless. In this connection, the measurement of the conductivity isconducted at 25° C. using a conductivity meter (a personal SC meterModel SC72 and a detector SC72SN-11 manufactured by Yokogawa ElectricCorporation).

Moreover, at the time when a pigment is mixed with the emulsioncontaining the polymer primary particles, wax may be mixed with theemulsion. As the wax, those the same as described in the explanation ofthe emulsion polymerization process can be used. The wax may be mixed atany time before, during, or after the pigment is mixed with the emulsioncontaining the polymer primary particles.

Also, at the time when a pigment is mixed with the emulsion containingthe polymer primary particles, a charge control agent may be mixed withthe emulsion.

As the charge control agent, any one known to be usable in thisapplication can be used. Examples of a positively charged charge controlagent include nigrosine-based dyes, quaternary ammonium salts,triphenylmethane-based compounds, imidazole-based compounds, polyamineresins, and the like. Moreover, examples of a negatively charged chargecontrol agent include azo complex compound dyes containing an atom suchas Cr, Co, Al, Fe, or B; metal salts or metal complexes of salicylicacid or alkylsalicylic acid; carixarene compounds, metal salts or metalcomplexes of benzylic acid, amide compounds, phenol compounds, naphtholcompounds, phenolamide compounds, and the like. Of these, in order toavoid tone disorder as a toner, colorless or light color one ispreferably selected. Of these, in order to avoid color tone disorder,colorless or hypochromic ones are preferably selected. Particularly, asthe positively charged charge control agent, quaternary ammonium saltsand imidazole-based compounds are preferred and, as the negativelycharged charge control agent, alkylsalicylic acid complex compoundscontaining an atom such as Cr, Co, Al, Fe, or B and carixarene compoundsare preferred. The charge control agent may be used singly or two ormore thereof may be used in combination at any combination and in anyratio.

There is no limitation on the amount of the charge control agent to beused but the amount is usually 0.01 part by weight or more, preferably0.1 part by weight or more and 10 parts by weight or less, preferably 5parts by weight or less relative to 100 parts by weight of the polymer.When the amount of the charge control agent is too small or too large,there is a possibility that a desired charge amount is not obtained.

The charge control agent may be mixed at any time before, during, orafter the pigment is mixed with the emulsion containing the polymerprimary particles.

Moreover, the charge control agent is desirably mixed at agglomerationin an emulsion state in a liquid medium (usually an aqueous medium) asin the case of the above pigment particles.

After the pigment is mixed with the emulsion containing the abovepolymer primary particles, the polymer primary particles and the pigmentare agglomerated. As mentioned above, the pigment is usually mixed as apigment particle dispersion at mixing.

The agglomeration method is not limited and arbitrary but, for example,heating, mixing of an electrolyte, pH regulation, and the like arementioned. Of these, a method of mixing an electrolyte is preferred.

As the electrolyte in the case of agglomeration by mixing theelectrolyte, there may be, for example, chlorides such as NaCl, KCl,LiCl, MgCl₂, and CaCl₂; inorganic salts including sulfate salts such asNa₂SO₄, K₂SO₄, Li₂SO₄, MgSO₄, CaSO₄, ZnSO₄, Al₂(SO₄)₃, and Fe₂(SO₄)₃;organic salts such as CH₃COONa, C₆H₅SO₃Na; and the like. Of these,inorganic salts having a divalent to polyvalent metal cation arepreferred.

The electrolyte may be used singly or two or more thereof may be used incombination at any combination and in any ratio.

The amount of the electrolyte to be used varies depending on the kind ofthe electrolyte but is usually 0.05 part by weight or more, preferably0.1 part by weight or more and usually 25 parts by weight or less,preferably 15 parts by weight or less, more preferably 10 parts byweight or less relative to 100 parts by weight of solid components inthe emulsion. In the case where the electrolyte is mixed to effectagglomeration, when the amount of the electrolyte to be used is toosmall, the proceeding of the agglomeration reaction becomes slow andthere is a possibility that fine powder of 1 μm or less remains afterthe agglomeration reaction or average particle size does not reachobjective particle size. When the amount of the electrolyte to be usedis too large, the agglomeration reaction rapidly occurs and hence thecontrol of the particle size becomes difficult, so that there is apossibility that coarse powder and amorphous one are contained in theresulting agglomerate.

The resulting agglomerate is preferably transformed into spherical oneby subsequently heating it in the liquid medium as in the case of asecondary agglomerate (an agglomerate passed through a melting step) tobe mentioned below. Heating may be carried out in the same conditions asin the case of the secondary agglomerate (the same conditions asdescribed in the explanation of the fusion step).

On the other hand, in the case of conducting the agglomeration byheating, the temperature condition is arbitrary so long as theagglomeration proceeds. With regard to the specific temperaturecondition, the agglomeration is conducted under a temperature conditionof usually 15° C. or higher, preferably 20° C. or higher and the glasstransition temperature [Tg] of the polymer of the polymer primaryparticles or lower, preferably 55° C. or lower. The time required foragglomeration is also arbitrary but is usually 10 minutes or more,preferably 60 minutes or more and usually 300 minutes or less,preferably 180 minutes or less.

At the agglomeration, it is preferred to carry out stirring. The deviceto be used for stirring is not particularly limited but one havingdouble helical blades is preferred.

The resulting agglomerate may be subjected to the next step where aresin coating layer is formed (encapsulation step) without furthertreatment or may be subjected to the encapsulation step after subsequentfusion treatment by heating is carried out in the liquid medium.Desirably, it is preferred to conduct the encapsulation step after theagglomeration step and then to conduct the fusion step by heating theencapsulated resin fine particles to a temperature higher than the glasstransition temperature [Tg] of the fine particles or higher since thesteps can be simplified and deterioration (thermal deterioration) of theperformance of the toner does not occur.

3. Encapsulation Step

After the agglomerate is obtained, on the agglomerate, it is preferredto form a resin coating layer according to need. The encapsulation stepwhere a resin coating layer is formed on the agglomeration is a stepwhere the agglomerate is coated with a resin by forming a resin coatinglayer on the surface of the agglomerate. Thereby, the produced toner isprovided with the resin coating layer. In the encapsulation step, thereis a case where the whole toner is not completely coated but there canbe obtained a toner wherein the pigment is substantially not exposed onthe surface of the toner particles. The thickness of the resin coatinglayer on this occasion is not limited but is usually in the range of0.01 to 0.5 μm.

The method for forming the above resin coating layer is not particularlylimited but there may be, for example, mentioned a spray dry method, amechanical particle complicating method, an in-situ polymerizationmethod, a in-liquid particle coating method, and the like.

As the method for forming the resin coating layer by the above spray drymethod, for example, a resin coating layer can be formed on theagglomerate surface by dispersing the agglomerate that forms an innerlayer and resin fine particles that forms the resin coating layer in awater medium to prepare a dispersion liquid and subsequently sprayingthe dispersion liquid, followed by drying.

Moreover, the method for forming the resin coating layer by the abovemechanical particle complicating method includes, for example, a methodof dispersing the agglomerate that forms an inner layer and resin fineparticles that forms the resin coating layer in a gas phase andconverting the resin fine particles into a film on the agglomeratesurface by imparting a mechanical force in a narrow gap. For example, anapparatus such as a hybridization system (manufactured by Nara MachineryCo., Ltd.), a mechanofusion system (manufactured by Hosokawa MicronCorp.), and the like can be employed.

Furthermore, the above in-situ polymerization method includes, forexample, a method of forming a resin coating layer on the surface of theagglomerate as an inner layer, which comprises dispersing theagglomerate in water, mixing a monomer and an polymerization initiatorto adsorb them on the surface of the agglomerate, and subsequentlyheating the whole to polymerize the monomer.

Additionally, the above in-liquid particle coating method includes, forexample, a method of reacting or binding the agglomerate that forms aninner layer and resin fine particles that forms an outer layer in awater medium to form a resin coating layer on the surface of theagglomerate that forms an inner layer.

The resin fine particles to be used in the case of forming the outerlayer are particles having a particle size smaller than that of theagglomerate and mainly composed of a resin component. The resin fineparticles are not particularly limited so long as the particles isconstituted by a polymer. However, in view of controlling the thicknessof the outer layer, it is preferred to use resin fine particles similarto the aforementioned polymer primary particles, agglomerate, or fusedparticles formed by fusing the above agglomerate. In this connection,the resin fine particles similar to these polymer primary particles,etc. can be produced similarly to the polymer primary particles in theagglomerate to be used for the inner layer.

Moreover, the amount of the resin fine particles is arbitrary but theparticles are desirably used in the range of usually 1% by weight ormore preferably 5% by weight or more and usually 50% by weight or less,preferably 25% by weight or less relative to the toner particles.

Furthermore, in order to effectively conduct adhesion or fusion of theresin fine particles to the agglomerate, with regard to the particlesize of the resin fine particles, particles having the size of about0.04 to 1 μm are preferably used.

Desirably, the glass transition temperature [Tg] of the polymercomponent (resin component) to be used for the resin coating layer isusually 60° C. or higher, preferably 70° C. or higher and usually 110°C. or lower. Furthermore, the glass transition temperature [Tg] of thepolymer component to be used for the resin coating layer is preferablynot less than 5° C., more preferably not less than 10° C. higher thanthe glass transition temperature [Tg] of the polymer primary particles.When the glass transition temperature [Tg] is too low, the storage ingeneral environment is difficult, while when the temperature is toohigh, a sufficient melting ability is not obtained, so that the casesare not preferred.

Furthermore, it is preferred to contain polysiloxane wax in the resincoating layer. Thereby, an advantage of improved high-temperature offsetresistance can be obtained. Examples of the siloxane wax includesilicone waxes having an alkyl group, and the like.

The content of the siloxane wax is not limited but is, in the toner,usually 0.01% by weight or more, preferably 0.05% by weight or more,more preferably 0.08% by weight or more and usually 2% by weight orless, preferably 1% by weight or less, more preferably 0.5% by weight ofless. When the amount of the polysiloxane wax is too small, there is apossibility that the high-temperature offset resistance becomesinsufficient, while when the amount is too large, there is a risk thatblocking resistance may decrease.

The method for incorporating the polysiloxane wax into the resin coatinglayer is arbitrary but, for example, emulsion polymerization is carriedout using the polysiloxane wax as a seed and the resulting resin fineparticles and the agglomerate that forms an inner layer are reacted orbonded in an aqueous medium to form a resin coating layer containing thepolysiloxane wax on the surface of the agglomerate that forms an innerlayer, thereby it being possible to incorporate the wax.

4. Fusion Step

In the fusion step, the polymer constituting the agglomerate is fusedand integrated by heating the agglomerate.

In the case where encapsulated resin fine particles are formed byfoaming a resin coating layer on the agglomerate, fusion integration ofthe polymer constituting the agglomerate and the resin coating layerthereon is achieved by heating. Thereby, the pigment particles areobtained in a state substantially not exposed on the surface.

The temperature for the heating in the fusion step is a temperature ofglass transition temperature [Tg] of the polymer primary particlesconstituting the agglomerate or higher. Moreover, in the case where aresin coating layer is formed, the temperature is a temperature of theglass transition temperature [Tg] of the polymer component constitutingthe resin coating layer or higher. Specific temperature condition isarbitrary but it is preferably not less than 5° C. higher than the glasstransition temperature [Tg] of the polymer component constituting theresin coating layer. The upper limit is not limited but is preferably a“temperature 50° C. higher than the glass transition temperature [Tg] ofthe polymer component constituting the resin coating layer” or lower.

The time for heating depends on processing ability and the amount to beproduced but is usually from 0.5 to 6 hours.

5. Washing/Drying Step

In the case where the aforementioned each step is carried out in aliquid medium, after the fusion step, a toner can be obtained byremoving the liquid medium through washing and drying the resultingencapsulated resin particles. The method for washing and drying is notlimited and is arbitrary.

[Physical Properties Relating to Toner Particle Size]

The volume-average particle size [Dv] of the toner of the invention isnot limited and is arbitrary unless it remarkably impairs the advantagesof the invention but is usually 4 μm or more, preferably 5 μm or moreand usually 10 μm or less, preferably 8 μm or less. When thevolume-average particle size [Dv] of the toner is too small, there is apossibility that the stability of the image quality may decrease, whilewhen it is too large, there is a risk that resolution may decrease.

Moreover, with regard to the toner of the invention, it is desirablethat a value [Dv/Dn] obtainable by dividing the volume-average particlesize [Dv] by number-average particle size [Dn] is usually 1.0 or moreand usually 1.25 or less, preferably 1.20 or less, more preferably 1.15or less. The value [Dv/Dn] shows a state of particle size distributionand the value closer to 1.0 shows sharp particle size distribution. Thesharper particle size distribution is desirable since the chargingproperty of the toner becomes uniform.

Furthermore, with regard to the toner of the invention, a volumefraction of the particles having a particle size of 25 μm or more isusually 1% or less, preferably 0.5% or less, more preferably 0.1% orless, further preferably 0.05% or less. The smaller value is morepreferred. This means that the ratio of the coarse powder contained inthe toner is small. When the ratio of the coarse powder is small, theconsumed amount of the toner at continuous development is small and theimage quality is stabilized, so that the case is preferred. In thisconnection, entirely no presence of the coarse powder having a particlesize of 25 μm or more is most preferred but achievement thereof isdifficult at actual production and usually, there arises no trouble evenwhen the ratio is not 0.005% or less.

Moreover, with regard to the toner of the invention, a volume fractionof the particles having a particle size of 15 μm or more is usually 2%or less, preferably 1% or less, more preferably 0.1% or less. Entirelyno presence of the coarse powder having a particle size of 15 μm or moreis also most preferred but achievement thereof is difficult at actualproduction and usually, there arises no trouble even when the ratio isnot 0.01% or less.

Furthermore, desirably, with regard to the toner of the invention, anumber fraction of the particle having a particle size of 5 μm or lessis usually 15% or less, preferably 10% or less since image fogging isimproved.

The volume-average particle size [Dv], number-average particle size[Dn], volume fraction, number fraction, and the like can be measured asfollows. Namely, a multisizer type II or III of Coulter counter(manufactured by Beckman Coulter Co.) is used as a measuring apparatusof particle size of the toner, which is used through connection to aninterface that outputs number distribution and volume distribution and ageneral personal computer. As an electrolytic solution, Isoton II isused. As a measuring method, 0.1 to 5 mL of a surfactant (preferablyalkylbenzenesulfonate salt) as a dispersant is added into 100 to 150 mLof the above electrolytic solution and 2 to 20 mg of a sample to bemeasured (toner) is further added thereto. Then, the electrolyticsolution containing the suspended sample is subjected to dispersiontreatment on an ultrasonic dispersing device for about 1 to 3 minutesand then measurement is conducted by means of the above multisizer typeII or III of Coulter counter using a 100 μm aperture. Thus, the numberand volume of the toner are measured and the number distribution andvolume distribution are calculated respectively, followed bydetermination of respective volume-average particle size [Dv] andnumber-average particle size [Dn].

[Physical Properties Relating to Molecular Weight of Toner]

At least one of the peak molecular weights of THF-soluble part of thetoner of the invention in gel permeation chromatography is usually10,000 or more, preferably 20,000 or more, more preferably 30,000 ormore and usually 150,000 or less, preferably 100,000 or less, morepreferably 70,000 or less. In this connection, THF meanstetrahydrofuran. In the case where all the peak molecular weights arelower than the above range, mechanical durability in a nonmagneticone-component developing mode becomes worse in some cases, while whenall the peak molecular weights are higher than the above range, thelow-temperature fixing ability and fixing strength sometimes becomesworse.

Furthermore, a THF-insoluble part is usually 10% or more, preferably 20%or more and usually 60% or less, preferably 50% or less when measured bythe weight method through celite filtration to be mentioned below. Whenthe amount is out of the range, both of the mechanical durability andthe low-temperature fixing ability are difficult to achievesimultaneously in some cases.

In this connection, the peak molecular weight of the toner of theinvention is measured using a measuring apparatus: HLC-8120GPC(manufactured by Tosoh Corporation) under the following conditions.

Namely, columns are stabilized in a heat chamber at 40° C. andtetrahydrofuran (THF) as a solvent is passed through the columns at thetemperature at a rate of 1 mL per minute. Then, after the toner isdissolved in THF, the solution is filtrated through a 0.2 μm filter andthe filtrate is used as a sample.

The measurement is carried out by injecting 50 to 200 μL of a THFsolution of a resin into the measuring apparatus, the sampleconcentration (concentration of the resin) being adjusted to 0.05 to0.6% by mass. At the molecular weight measurement of the sample (a resincomponent in the toner), the molecular weight distribution of the sampleis calculated based on the relation between the logarithmic value andthe count number in the calibration curve prepared with several kinds ofmonodisperse polystyrene standard samples. As the standard polystyrenesamples for calibration curve preparation, for example, those having amolecular weight of 6×10², 2.1×10³, 4×10³, 1.75×10⁴, 5.1×10⁴, 1.1×10⁵,3.9×10⁵, 8.6×10⁵, 2×10⁶, or 4.48×10⁶ manufactured by Pressure ChemicalCo. or Tosoh Corporation are used and it is suitable to use at leastabout 10 samples of the standard polystyrene samples. Moreover, an RI(refractive index) detector is used as a detector.

Furthermore, as columns to be used in the above measuring method, inorder to measure the molecular weight region of 10³ to 2×10⁶ precisely,two or more commercially available polystyrene gel columns are suitablycombined and, for example, a combination of μ-styragel 500, 103, 104,and 105 (manufactured by Waters Co.) or a combination of shodex KA801,802, 803, 804, 805, 806, and 807 (manufactured by Showa Denko Co.) ispreferred.

Moreover, the measurement of tetrahydrofuran (THF)-insoluble part of thetoner can be carried out as follows. Namely, 1 g of the sample (toner)is added to 100 g of THF and the whole was allowed to stand at 25° C.for 24 hours for dissolution. After filtration using 10 g of celite, thesolvent of the filtrate is removed by filtration and a THF-soluble partis quantitatively determined. Then, a THF insoluble part can becalculated by subtracting the weight of the THF-soluble part from 1 g.

[Softening Point and Glass Transition Temperature of Toner]

The softening point [Sp] of the toner of the invention is not limitedand is arbitrary unless it remarkably impairs the advantages of theinvention. However, in view of fixing at low energy, the softening pointis usually 150° C. or lower, preferably 140° C. or lower. Moreover, inview of high-temperature offset property and durability, the softeningpoint is usually 80° C. or higher, preferably 100° C. or higher.

In this connection, the softening point [Sp] of the toner can bedetermined as a temperature at a middle point of a strand from the startand finish of flow when 1.0 g of a sample is measured under conditionsof a nozzle of 1 mm×10 mm, a load of 30 kg, a preheating time of 5minutes at 50° C., and a temperature-elevating rate of 3° C./minute in aflow tester.

Moreover, the glass transition temperature [Tg] of the toner of theinvention is not limited and is arbitrary unless it remarkably impairsthe advantages of the invention but desirably, it is usually 80° C. orlower, preferably 70° C. or lower since fixing can be achieved at lowenergy. Moreover, desirably, the glass transition temperature [Tg] isusually 40° C. or higher, preferably 50° C. or higher in view ofblocking resistance.

In this connection, the glass transition temperature [Tg] of the tonercan be determined as a temperature at a crossing point of two tangentlines when the tangent lines are drawn at transition (inflection) startpoints of a curve measured under a temperature-elevating rate of 10°C./minute in a differential scanning calorimeter.

The softening point [Sp] and the glass transition temperature [Tg] ofthe toner is remarkably influenced by the kind and composition ratio ofthe polymer contained in the toner. Therefore, the softening point [Sp]and the glass transition temperature [Tg] of the toner can be adjustedby suitably controlling the kind and composition of the above polymer.Moreover, it is possible to adjust them by the molecular weight of thepolymer, gel component, and the kind and mixing amount of low-meltingcomponents such as wax.

[Wax in Toner]

In the case where the toner contains wax, the dispersion particle sizeof the wax in the toner particles is, as an average particle size,usually 0.1 μm or more, preferably 0.3 μm or more and an upper limit isusually 3 μm or less, preferably 1 μm or less. When the dispersionparticle size is too small, there is a possibility that an effect ofimproving filming resistance of the toner may not be obtained, whilewhen the dispersion particle size is too large, the wax tends to beexposed on the surface of the toner, so that charging property and heatresistance may decrease.

The dispersion particle size of the wax can be confirmed by a method oftransforming the toner into a slice and observing it on an electronmicroscope and also by a method of eluting the polymer in the toner withan organic solvent or the like which does not dissolve the wax,filtrating the whole through a filter, and measuring wax particles whichremain on the filter.

Moreover, the ratio of the wax in the toner is arbitrary unless itremarkably impairs the advantages of the invention but is usually 0.05%by weight or more, preferably 0.1% by weight or more and usually 20% byweight or less, preferably 15% by weight or less. When the amount of thewax is too small, the range of the fixing temperature may becomeinsufficient, while when the amount is too large, there is a possibilitythat the wax may stain the device members to lower image quality.

[Externally Adding Fine Particles]

In order to improve fluidity, charging stability, and blockingresistance at high temperature of the toner, externally adding fineparticles may be attached to the surface of the toner particles.

As a method for attaching the externally adding fine particles to thesurface of the toner particles, for example, in the aforementionedprocess for producing the toner, there may be mentioned a method ofadhering the externally adding fine particles on the toner particles byheating after mixing the secondary agglomerate and the externally addingfine particle in the liquid medium; a method of mixing or adhering theexternally adding fine particles in a dry manner with the tonerparticles obtained by separating secondary agglomerate from the liquidmedium and washing and drying the agglomerate; and the like.

Examples of the mixing machine to be used in the case of mixing thetoner particles and the externally adding fine particles in a dry mannerinclude Henschel mixer, super mixer, Nauter mixer, V type mixer, redeigemixer, double corn mixer, drum type mixer, and the like. Of these,mixing is preferably achieved by homogeneously stirring and mixing withsuitably setting blade shape, rotation number, time, number ofdriving-stopping, and the like using a high-speed mixing machine such asHenschel mixer or super mixer.

Moreover, as an apparatus to be used in the case of adhering the tonerparticles and the externally adding fine particles in a dry manner,there may be mentioned a compressive shear treatment apparatus capableof imparting compressive shear stress, a particle surface fusiontreatment apparatus capable of fusing the particle surface, and thelike.

The compressive shear treatment apparatus generally has a narrow gappart constituted by a head face which relatively moves with keeping aspace and a head face, a head face and a wall face, or a wall face and awall face and is constituted so that compressive stress and shear stressare imparted to the particle surface by compulsorily passing particlesto be treated through the gap part, without substantial pulverization.As such a compressive shear treatment apparatus, there may be, forexample, a mechanofusion apparatus manufactured by Hosokawa Micron Corp.and the like.

On the other hand, the particle surface fusion treatment apparatus isgenerally constituted so that a mixture of mother fine particles and theexternally adding fine particles is instantaneously heated tomelt-starting temperature of the mother fine particles or higher toadhere the externally adding fine particles utilizing hot air flow orthe like. As such a particle surface fusion treatment apparatus, theremay be, for example, mentioned a surfusing system manufactured by NipponPneumatic Mfg. Co., Ltd. and the like.

Moreover, as the externally adding fine particles, a known one which isknown to be usable in this application can be used. For example,inorganic fine particles, organic fine particles, and the like may bementioned.

As the inorganic fine particles, there may be used carbides such assilicon carbide, boron carbide, titanium carbide, zirconium carbide,hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide,tungsten carbide, chromium carbide, molybdenum carbide, and carciumcarbide; nitrides such as boron nitride, titanium nitride, zirconiumnitride, and silicon nitride; borides such as zirconium boride; oxidesand hydroxides such as silica, colloidal silica, titanium oxide,aluminum oxide, calcium oxide, magnesium oxide, zinc oxide, copperoxide, zirconium oxide, cerium oxide, talc, and hydrotalcite; varioustitanate compounds such as calcium titanate, magnesium titanate,strontium titanate, barium titanate; phosphate compounds such astricalcium phosphate, calcium dihydrogen phosphate, calcium monohydrogenphosphate, substituted calcium phosphate where part of phosphate ions issubstituted by anion(s); sulfides such as molybdenum disulfide;fluorides such as magnesium fluoride and carbon fluoride; metal soapssuch as aluminum stearate, calcium stearate, zinc stearate, andmagnesium stearate; talcite, bentonite, various carbon blacks such asconductive carbon black; and the like. In addition, magnetic substancessuch as magnetite, maghematite, intermediates of magnetite andmaghematite and the like may be used.

On the other hand, as the organic fine particles, there may be used fineparticles of styrene-based resins, acrylic resins such as polymethylacrylate and polymethyl methacrylate, epoxy resins, melamine resins,tetrafluoroethylene resins, trifluoroethylene resins, polyvinylchloride, polyethylene, polyacrylonitrile, and the like.

Among these externally adding fine particles, particularly, silica,titanium oxide, alumina, zinc oxide, carbon black, and the like aresuitably used.

In this connection, the externally adding fine particles may be singlyor two or more thereof may be used in combination at any combination andin any ratio.

Moreover, the surface of these inorganic or organic fine particles maybe subjected to surface treatment such as hydrophobic treatment with atreating agent such as a silane coupling agent, a titanate-basedcoupling agent, a silicone oil, a modified silicone oil, a siliconevarnish, a fluorinated silane coupling agent, a fluorinated siliconeoil, or a coupling agent having an amino group or a quaternary ammoniumsalt group. The treating agent may be singly or two or more thereof maybe used in combination at any combination and in any ratio.

Furthermore, the number-average particle size of the externally addingfine particles is arbitrary unless it remarkably impairs the advantagesof the invention but is usually 0.001 μm or more, preferably 0.005 μm ormore and usually 3 μm or less, preferably 1 μm or less. Two or more ofthe particles having different average particle sizes may be mixed. Inthis connection, the average particle size can be determined byobservation on an electron microscope, conversion of the value of BETspecific surface area, or the like.

Moreover, the ratio of the externally adding fine particles to the toneris arbitrary unless it remarkably impairs the advantages of theinvention. However, it is desirable that the ratio of the externallyadding fine particles to the total weight of the toner and theexternally adding fine particles is usually 0.1% by weight or more,preferably 0.3% by weight or more, more preferably 0.5% by weight ormore and usually 10% by weight or less, preferably 6% by weight or less,more preferably 4% by weight or less. When the amount of the externallyadding fine particles is too small, there is a possibility that fluidityand charging stability may be insufficient, while when it is too large,there is a possibility that fixing ability becomes worse.

[Miscellaneous]

The charging property of the toner of the invention may be negativecharging or positive charging and can be set depending on the mode ofthe image-forming device to be used. The charging property of the tonercan be regulated by selection and composition ratio of the motherparticle-constituting substance of the charge control agent, selectionand composition ratio of the externally adding fine particles, and thelike.

Moreover, the toner of the invention can be used as a one-componentdeveloper or as a two-component developer mixed with a carrier.

In the case of the use as the two-component developer, as the carrierwhich is mixed with the toner to form a developer, for example, magneticsubstances such as known iron powder-based, ferrite-based,magnetite-based carriers or those obtained by subjecting the surfacethereof to resin coating and magnetic resin carriers can be used.

As the coating resin for the carriers, for example, commonly knownstyrene-based resins, acrylic resins, styrene/acrylic copolymer resins,silicone-based resins, modified silicone-based resins, fluorinatedresins, and the like can be utilized but the resin is not limitedthereto.

Moreover, the average particle size of the carrier is not particularlylimited but those having an average particle size of 10 to 200 μm arepreferred. These carriers are preferably used in a ratio of 5 to 100parts by weight relative to 1 part by weight of the toner.

Meanwhile, the formation of full-color images by an electrophotographicprocedure can be carried out in a usual manner using individual colortoners of magenta, cyan, and yellow and, if necessary, a black toner.

There is no limitation on the kind of the transfer device 5 and it ispossible to use various devices employing any methods includingelectrostatic transfer methods such as corona transfer, roller transfer,and belt transfer; pressure transfer method; and adhesive transfermethod. In this embodiment, the transfer device 5 is constituted by atransfer charger, a transfer roller, a transfer belt, and the like,which are diposed facing the electrophotographic photoreceptor 1. Thetransfer device 5 applies a predetermined voltage (transfer voltage)having a reverse polarity to the electric potential charged to the tonerT to thereby transfer the toner image formed on the electrophotographicphotoreceptor 1 onto a recording paper (form, medium) P.

The cleaning device 6 is not particularly limited and it is possible touse any cleaning devices including brush cleaners, magnetic brushcleaners, electrostatic brush cleaners, magnetic roller cleaners, andblade cleaners. The cleaning device 6 scrapes away residual tonerattached to the photoreceptor 1 by means of a cleaning member to collectthe residual toner. The cleaning device 6 may be omitted in the casewhere only a small amount or almost no amount of residual toner appears.

The fixing device 7 comprises an upper fixing member (fixing roller) 71and a lower fixing member (fixing roller) 72, and a heating device 73 isdisposed at the inside of either fixing member 71 or 72. FIG. 1illustrates an example in which the heating device 73 is provided at theinside of the upper fixing member 71. As each of the upper and lowerfixing member 71, 72, it is possible to use various known heat fixingmembers including a fixing roll in which a metal tube such as stainlessor aluminum is coated with silicone rubber, a fixing roll further coatedwith Teflon (registered trademark) resin, a fixing sheet, etc. Inaddition, the fixing members 71, 72 may be configured to provide a moldrelease agent such as a silicone oil for improving mold releasingability, and also may be forced to exert pressure on each other by meansof a spring or the like.

The toner transferred onto the paper P is passes through the upperfixing member 71 and the lower fixing member 72 heated at apredetermined temperature, during which passage the toner is heated andbrought into a fused state. After the passage, the toner is then cooledand fixed on the recording paper P.

There is no particular limitation on the selection of the fixing device,which may employ any methods, e.g., the method used in the above andheat-roller fixing, flash fixing, oven fixing, pressure fixing, and thelike.

In the image-forming device constituted above, image recording iscarried out according to the following manner (image-forming method ofthe invention).

Namely, the surface of the photoreceptor 1 (photosensitive surface) iselectrically charged to a predetermined potential (e.g., −600V) by thecharging device 2. The charging may be carried out either using a directcurrent voltage or using a current in which a direct current voltage issuperimposed on an alternating current voltage.

Subsequently, the charged photosensitive surface of the photoreceptor 1is then subjected to exposure by the exposing device 3 in accordancewith an image to be recorded, so that an electrostatic latent image isformed on the photosensitive surface. Then, the electrostatic latentimage formed on the photosensitive surface of the photoreceptor 1undergoes development by the developing device 4.

In the developing device 4, the toner T provided by the feeding roller43 is made into the form of a thin layer by the regulating member(developing blade) 45 while being charged with a predetermined polarity(in the embodiment, the same polarity as that of the potential chargedto the photoreceptor 1, i.e., negative polarity) through frictionalcharging. The toner is then carried and transferred by the developingroller 44 and brought into contact with the surface of the photoreceptor1.

When the charged toner T carried by the developing roller 44 is comeinto contact with the surface of the photoreceptor 1, a toner imagecorresponding to the electrostatic latent image is formed on thephotosensitive surface of the photoreceptor 1. The toner image is thentransferred onto the recording paper P by the transfer device 5, afterwhich the cleaning device 6 removes the residual toner that stays on thephotosensitive surface of the photoreceptor 1 without being transferred.

Subsequently to the transfer of the toner image onto the paper P, thetoner image is passed through the fixing device 7 and thermally fixed onthe recording paper P, whereby the ultimate image is obtained.

The image-forming device may be configured to carry out an erase step inaddition to the aforementioned configuration. The erase step is a stepof removing electrical charge of the electrophotographic photoreceptorthrough exposure of the electrophotographic photoreceptor. As theerasing device, a fluorescent lamp, LED, or the like may be used. Thelight used for the erase step frequently has exposure whose intensity isthree-times or more as high as that of the exposure light or stillhigher in many cases.

Also, the image-forming device may be constituted with furthermodifications. For example, it may be configured to carry out anadditional steps such as a pre-exposure step or an auxiliary chargingstep, may be configured for offset printing, and may be configured as afull-color tandem type employing plural kinds of toners.

In this connection, it is also possible to use the electrophotographicphotoreceptor 1 singly or to combine the electrophotographicphotoreceptor 1 with any one or any two or more of the charging device2, the exposing device 3, the developing device 4, the transfer device5, the cleaning device 6, and the fixing device 7 to form anintegral-type cartridge (hereinafter, optionally referred to as“electrophotographic photoreceptor cartridge”), and to make theelectrophotographic photoreceptor cartridge detachable from andattachable to the main body of the image-forming device such as acopying machine or a laser-beam printer. In this case, using a cartridgecase configured to be detachable from and attachable to theimage-forming device, an electrophotographic photoreceptor cartridge canbe formed by casing and supporting the electrophotographic photoreceptor1 alone or in combination with the aforementioned elements. According tothe constitution, even when the electrophotographic photoreceptor 1 orany other component becomes deteriorated, for example, it becomespossible to detach the electrophotographic photoreceptor cartridge fromthe main body of the image-forming device and attach a newelectrophotographic photoreceptor cartridge to the main body of theimage-forming device, thereby the maintenance and management of theimage-forming device being facilitated.

EXAMPLES

The present invention will be explained in further detail with referenceto Examples and Comparative Examples mentioned below. The followingExamples are mentioned for the sake of explaining the invention indetail, and the invention is not limited to the following Examplesunless it runs counter to the spirit of the invention.

[Conditions for Measuring Powder XRD Spectra and Calculating PeakHalfband Width]

The powder X-ray diffraction spectra of the phthalocyanines obtained inindividual Synthetic Examples and Comparative Synthetic Examples to bementioned below were measured by the following procedure. Namely, as ameasuring apparatus, PW1700 manufactured by PANalytical Co. was used,which is a convergent optical system powder X-ray diffractometer usingCuKα characteristic X-ray (wavelength of 1.541 angstrom) as a source.The measuring conditions are as follows: X-ray output 40 kV, 30 mA;scanning range (2θ) 3 to 40°; scan step width 0.05°; scanning rate3.0°/min; divergence slit 1.0°; dispersion slit 1.0°; and receiving slit0.2 mm.

The peak halfband width was calculated by a profile fitting method. Theprofile fitting was carried out using a powder X-ray diffractionpattern-analyzing software JADE5.0+ manufactured by MDI Co. Thecalculation conditions are as follows. Namely, background was fixed toan ideal position from the whole measuring range (2θ=3.0 to 40.0°). As afitting function, a Peason-VII function considering the contribution ofCuKα₂ was employed. As variables of the fitting function, threevariables, i.e., diffraction angle (2θ), peak height, peak halfbandwidth (β₀) were made precise. The influence of CuKα₂ was eliminated andthe diffraction angle (2θ), peak height, and peak halfband width (β₀)derived from CuKα₁ were calculated. Asymmetry is fixed to 0 and shapeconstant to 1.5.

The peak halfband width (β₀) calculated by the above profile fitting wascorrected in accordance with the following equation by the peak halfbandwidth (β_(Si)) of 111 peak (2 θ=28.442°) of standard Si (NIST Si 640b)calculated under the same measuring conditions and the same profilefitting conditions to thereby determine a peak halfband width (β)derived from the sample.β=√{square root over (β_(o) ²−β_(Si) ²)}  [Num 3]

Synthetic Example 1 (β Type Oxytitanium Phthalocyanine Crystal)

In accordance with the procedures of “Production Example and subsequent“Example 1” of Crude TiOPc” described in JP-A-10-7925, β typeoxytitanium phthalocyanine crystal was prepared. FIG. 6 shows a powderXRD spectrum of the resulting β type oxytitanium phthalocyanine crystal.Moreover, as a result of analyzing the chlorine content contained in theresulting β type oxytitanium phthalocyanine crystal in accordance withthe procedure described in the article of <Chlorine Content MeasuringConditions (Elemental Analysis)> of [Best Mode for Carrying Out theInvention] in the above, the chlorine content was found to be 0.20% byweight or less which is a lower detection limit or less. Furthermore,when the peak intensity ratio of chlorooxytitanium phthalocyanine tooxytitanium phthalocyanine in the resulting β type oxytitaniumphthalocyanine crystal was measured in accordance with the proceduredescribed in the article of <Mass Spectrum Measuring Condition> of [BestMode for Carrying Out the Invention] in the above, it was 0.002.

Synthetic Example 2 (Low-Crystalline Oxytitanium Phthalocyanine)

Fifty parts by weight of the β type oxytitanium phthalocyanine crystalobtained in Synthetic Example 1 was added into 1250 parts by weight of95% conc. sulfuric acid cooled to −10° C. or lower. On this occasion,the compound was slowly added so that the inner temperature of thesulfuric acid solution did not exceed −5° C. After the addition wasfinished, the conc. sulfuric acid solution was stirred for 2 hours at atemperature of −5° C. or lower. After stirring, the conc. sulfuric acidsolution was filtrated through a glass filter and insoluble matter wasremoved by filtration. Thereafter, the conc. sulfuric acid solution waspoured into 12,500 parts by weight of ice water to thereby precipitateoxytitanium phthalocyanine, followed by stirring for 1 hour afterpouring. After stirring, the solution was filtrated off and theresulting wet cake was again washed in 2500 parts by weight of water for1 hour, followed by filtration. The washing operation was repeated untilthe ion conductivity of the filtrate reached 0.5 mS/m to thereby obtain452 parts by weight of wet cake of low-crystalline oxytitaniumphthalocyanine (content of oxytitanium phthalocyanine: 11.1% by weight).FIG. 7 shows a powder XRD spectrum of the resulting oxytitaniumphthalocyanine crystal.

Examples 1 to 4, Comparative Synthetic Example 1

As a phthalocyanine crystal precursor, 33 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 2 was added into 90 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 13 parts byweight of each of respective compounds shown in the right column of thefollowing Table 2 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain crystalsconsisting of oxytitanium phthalocyanine alone (hereinafter, they areoptionally referred to as phthalocyanine crystals of Examples 1 to 4 andComparative Synthetic Example 1). FIGS. 8 to 12 show powder XRD spectraof the phthalocyanine crystals of Examples 1 to 4 and ComparativeSynthetic Example 1, respectively. As apparent from the powder XRDspectra of FIGS. 8 to 12, any of the phthalocyanine crystals of Examples1 to 4 and Comparative Synthetic Example 1 had a main diffraction peakat Bragg angle (2θ±0.2°) of 27.2° toward CuKα characteristic X-ray(wavelength 1.541 angstrom).

TABLE 2 Compound to be brought into contact with phthalocyanine crystalprecursor Example 1 3-chlorobenzaldehyde ⁽*⁾ Example 2m-anisbenzaldehyde ⁽*⁾ Example 3 2-fluorobenzaldehyde ⁽*⁾ Example 41-naphthobenzaldehyde ⁽*⁾ Comparative o-dichlorobenzene SyntheticExample 1 ⁽*⁾ aromatic aldehyde compound

Synthetic Example 3 (Low-Crystalline Phthalocyanine Composition)

The operations the same as in Synthetic Example 2 were carried outexcept that 50 parts by weight of the oxytitanium phthalocyanine crystalof Synthetic Example 1 used as a starting material in Synthetic Example2 was changed to a mixture of 47.5 parts by weight of the oxytitaniumphthalocyanine crystal of Synthetic Example 1 and 2.5 parts by weight ofnon-metal phthalocyanine (“FastgenBlue8120BS” manufactured by DainipponInk And Chemicals, Incorporated), thereby 410 parts by weight of wetcake of a low-crystalline phthalocyanine composition (content ofphthalocyanines: 12.2% by weight). FIG. 13 shows a powder XRD spectrumof the resulting low-crystalline phthalocyanines.

Examples 5 to 8, Comparative Synthetic Example 2

As a phthalocyanine crystal precursor, 33 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine composite obtained inSynthetic Example 3 was added into 90 parts by weight of water, followedby stirring at room temperature for 30 minutes. Thereafter, 13 parts byweight of each of respective compounds shown in the right column of thefollowing Table 3 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain mixed crystalsof oxytitanium phthalocyanine and metal-free phthalocyanine (they arereferred to as phthalocyanine crystals of Examples 5 to 8 andComparative Synthetic Example 2). FIGS. 14 to 18 show powder XRD spectraof the phthalocyanine crystals of Examples 5 to 8 and ComparativeSynthetic Example 2, respectively. As apparent from the powder XRDspectra of FIGS. 14 to 18, any of the phthalocyanine crystals ofExamples 5 to 8 and Comparative Synthetic Example 2 had a maindiffraction peak at Bragg angle (2θ±0.2°) of 27.2° toward CuKαcharacteristic X-ray (wavelength 1.541 angstrom).

TABLE 3 Compound to be brought into contact with phthalocyanine crystalprecursor Example 5 3-chlorobenzaldehyde ⁽*⁾ Example 6m-anisbenzaldehyde ⁽*⁾ Example 7 2-fluorobenzaldehyde ⁽*⁾ Example 81-naphthobenzaldehyde ⁽*⁾ Comparative o-dichlorobenzene SyntheticExample 2 ⁽*⁾ aromatic aldehyde compound[Process for Producing Photoreceptor]

Using a conductive substrate obtained by forming an aluminum depositedfilm (thickness: 70 nm) on the surface of a biaxially stretchedpolyethylene terephthalate resin film (thickness: 75 μm), a dispersionliquid for an undercoat layer prepared by the method shown below wasapplied on the deposited layer of the substrate with a bar coater sothat film thickness after drying was 1.25 μm and dried to form anundercoat leery.

The preparation of the dispersion liquid for an undercoat layer wascarried out by the following method. Namely, rutile type titanium oxidehaving an average primary particle size of 40 nm (“TTO55N” manufacturedby Ishihara Sangyo Kaisha, Ltd.) and 3 parts by weight ofmethyldimethoxysilane (“TSL8117” manufactured by Toshiba Silicone Co.,Ltd.) relative to the titanium oxide were charged into a high-speedflowing mixing kneader (“SMG300” manufactured by Kawata Mfg. Co., Ltd.),followed by high-speed mixing at a rotation peripheral velocity of 34.5m/second. The resulting surface-treated titanium oxide was dispersedinto metanol/1-propanol in a ball mill to form a dispersion slurry ofhydrophobic treated titanium oxide. The dispersion slurry, a mixedsolvent of methanol/1-propanol/toluene, and pellets of a copolymerpolyamide consisting of ε-caprolactam [a compound represented by thefollowing formula (A)]/bis(4-amino-3-methylcyclohexyl)methane [acompound represented by the following formula (B)]/hexamethylenediamine[a compound represented by the following formula(C)]/decamethylenedicarboxylic acid [a compound represented by thefollowing formula (D)]/octadecamethylenedicarboxylic acid [a compoundrepresented by the following formula (E)] in a compositional molar ratioof 60%/15%/5%/15%/5% were stirred and mixed under heating to dissolvethe polyamide pellets. Thereafter, the whole was subjected to ultrasonicdispersion treatment to thereby form a dispersion liquid for anundercoat layer having a solid concentration of 18.0% wherein a weightratio of methanol/1-propanol/toluene was 7/1/2 and the hydrophobictreated titanium oxide/the copolymer polyamide were contained in aweight ratio of 3/1.

On the other hand, using 20 parts by weight of each phthalocyaninecrystal to be mentioned below as a charge generation substance, it wasmixed with 280 parts by weight of 1,2-dimethoxyethane and the mixturewas pulverized in a sand grind mill for 2 hours to conduct fine particleformation/dispersion treatment. Moreover, 10 parts by weight ofpolybutyral (trade name “Denka butyral” #6000C manufactured by DenkiKagaku Kogyo K.K.) was dissolved into a mixed solution of 253 parts byweight of 1,2-dimethoxyethane and 85 parts by weight of4-methoxy-4-methyl-2-pentanone to prepare a binder solution. The finelydispersed treatment solution obtained by the aforementioned fineparticle formation/dispersion treatment and the above binder solutionwere mixed with 230 parts by weight of 1,2-dimethoxyethane to prepare acoating solution for a charge generation layer. The coating solution fora charge generation layer was applied on the undercoat layer formed onthe above conductive substrate with a bar coater so that film thicknessafter drying was 0.4 μm and then dried to form a charge generationlayer.

Furthermore, 50 parts by weight of a mixture consisting of a compoundgroup of geometric isomers synthesized based on Example 1 ofJP-A-2002-80432 and containing a structure represented by the followingstructural formula (F) as a main component was used as a chargetransport substance, 100 parts by weight of a polycarbonate resinconsisting of 51% by mol of a repeating unit of2,2-bis(4-hydroxy-3-methylphenyl)propane represented by the followingstructural formula (G) as an aromatic diol component and 49% by mol of arepeating unit of 1,1-bis(4-hydroxyphenyl)-1-phenylethane represented bythe following structural formula (H) as an aromatic diol component andhaving a terminal structural formula derived from p-t-butylphenol wasused as a binder resin. The above substances and additionally, 8 partsby weight of 2,6-di-t-butyl-4-methylphenol, 0.03 part by weight of asilicone oil (trade name “KF96” manufactured by Shin-Etsu Chemical Co.,Ltd.) were dissolved in 640 parts by weight mixed solvent oftetrahydrofuran/toluene (weight ratio 8/2) to prepare a coating solutionA for a charge transport layer. The coating solution for a chargetransport layer was applied on the resin film having the chargegeneration layer provided thereon so that film thickness after dryingwas 25 μm and then dried to form a charge transport layer, thereby anelectrophotographic photoreceptor having a multilayer photosensitivelayer being prepared.

Examples 9 to 16, Comparative Examples 1, 2

Using phthalocyanine crystals of Examples 1 to 8 and ComparativeSynthetic Examples 1 and 2 as charge generation substances,electrophotographic photoreceptors were produced in accordance with theaforementioned process for producing the photoreceptor (hereinafter,they are optionally referred to as electrophotographic photoreceptors ofExamples 9 to 16 and Comparative Examples 1 and 2). The correspondenceof each electrophotographic photoreceptor to the phthalocyanine crystalused as the charge generation substance and a composition thereof wasshown in the following Table 4.

TABLE 4 Electrophotographic Charge generation substance photoreceptor(phthalocyanine crystal) Example 9 Example 1 Crystals Example 10 Example2 consisting of Example 11 Example 3 oxytitanium Example 12 Example 4phthalocyanine Comparative Comparative Synthetic alone Example 1 Example1 Example 13 Example 5 Mixed crystals of Example 14 Example 6oxytitanium Example 15 Example 7 phthalocyanine Example 16 Example 8 andmetal-free Comparative Comparative Synthetic phthalocyanine Example 2Example 2[Evaluation of Electrophotographic Photoreceptor]

The electrophotographic photoreceptors of Examples 9 to 16 andComparative Examples 1 and 2 were mounted on an electrophotographicproperty-evaluating apparatus manufactured according to the standard ofthe Society of Electrophotography [“Zoku Denshishashin Gijutsu No KisoTo Oyo”, edited by the Society of Electrophotography, issued by CoronaPublishing Co. Ltd, pp. 404-405] and electrical properties wereevaluated through a cycle of charging, exposure, measurement ofpotential, and erase according to the following procedure.

A charging device was disposed at an angle of −70°, an exposing deviceat an angle of 0° C., a surface potentiometer probe at an angle of 36°,and an erasing device at an angle of −150° C. Individual devices weredisposed so that the distance from the photoreceptor surface was 2 mm.For the charging, a scorotron charing device was used. As an exposinglamp, a halogen lamp JDR110V-85WLN/K7 manufactured by Ushio, Inc. wasused and monochromatic light of 780 nm was formed using a filter MX0780manufactured by Asahi Spectra Co., Ltd. LED light of 660 nm was used asan erasing light.

The photoreceptor was charged with rotation at a constant rotation speed(60 rpm) so as that an absolute value of initial surface potential ofthe photoreceptor is −700 V. When the charged photoreceptor surfacepassed through an exposure portion irradiated with monochromatic lightof 780 nm and reached the probe position, the surface potential wasmeasured (time for exposure to potential measurement: 100 ms).

The monochromatic light of 780 nm was passed through ND filter to changelight intensity and the photoreceptor was irradiated with the light.Thus, irradiation energy (exposure) at the time when surface potentialreached −350 V was measured.

A value obtained by measuring the irradiation energy (exposure) underthe NN environment after being allowed to stand for 8 hours under the NNenvironment (unit: μJ/cm²) was regarded as standard-humidity sensitivity(hereinafter sometimes referred to as “En_(1/2)”) and a value obtainedby measuring the irradiation energy (exposure) under the NL environmentafter being allowed to stand for 8 hours under the NL environment (unit:μJ/cm²) was regarded as low-humidity sensitivity (hereinafter sometimesreferred to as “El_(1/2)”).

The sensitivity retention for a humidity change was calculated bycalculation according to the following equation using the resultingstandard humidity sensitivity En_(1/2) and low-humidity sensitivityEl_(1/2) (unit: %).Sensitivity retention (%) for humidity change=[Standard humiditysensitivity En _(1/2) (μJ/cm²)]/[low humidity sensitivity El _(1/2)(μJ/cm²)]×100  [Num 4]

The following Table 5 shows evaluation results of the electricalproperties on the electrophotographic photoreceptors of Examples 9 to 16and Comparative Examples 1 and 2.

TABLE 5 Standard- Low-humidity humidity Electrophotographic sensitivitysensitivity Sensitivity photoreceptor El_(1/2) (μJ/cm²) En_(1/2)(μJ/cm²) retention (%) Example 9 0.083 0.075 90.2 Example 10 0.085 0.07588.5 Example 11 0.091 0.084 91.9 Example 12 0.081 0.071 88.0 Comparative0.085 0.073 85.6 Example 1 Example 13 0.086 0.080 92.5 Example 14 0.0900.083 91.8 Example 15 0.095 0.088 93.1 Example 16 0.091 0.084 91.9Comparative 0.088 0.077 87.6 Example 2

As apparent from the powder XRD spectra (FIGS. 8 to 12 and 14 to 18),any of the phthalocyanine crystals of Examples 1 to 8 and ComparativeSynthetic Examples 1 and 2 were phthalocyanine crystals having a maindiffraction peak at Bragg angle (2θ±0.2°) of 27.2° toward CuKαcharacteristic X-ray (wavelength 1.541 angstrom).

These electrophotographic photoreceptors of Examples 9 to 16 andComparative Examples 1 and 2 using the phthalocyanine crystals ofExamples 1 to 8 and Comparative Synthetic Examples 1 and 2 as chargegeneration substances were divided into two groups {(crystals consistingof oxytitanium phthalocyanine alone: Examples 9 to 12 and ComparativeExample 1) and (mixed crystals of oxytitanium phthalocyanine andmetal-free phthalocyanine: Examples 13 to 16 and Comparative Example 2)}according to the composition of the phthalocyanine crystal. WhenExamples and Comparative Example are compared on each group, thestandard-humidity sensitivity El_(1/2) is equal to one another. However,when the values of the sensitivity retention are compared, theelectrophotographic photoreceptors of Examples show little fluctuationin sensitivity for a humidity change as compared with theelectrophotographic photoreceptors of Comparative Examples.

From the above results, it was evident that sensitivity fluctuation fora change in usage environment can be remarkably improved when thephthalocyanine crystals of Examples 1 to 4 and 5 to 8 obtained through astep of converting the crystal form by bringing a phthalocyanine crystalprecursor into contact with an aromatic aldehyde compound (i.e.,phthalocyanine crystals of the invention) were used forelectrophotographic photoreceptors.

Examples 17 to 22, Comparative Synthetic Examples 3 to 8

As a phthalocyanine crystal precursor, 38 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 2 was added into 100 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe respective aromatic compounds shown in the right column of thefollowing Table 6 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain crystalsconsisting of oxytitanium phthalocyanine alone (hereinafter, they areoptionally referred to as phthalocyanine crystals of Examples 17 to 22and Comparative Synthetic Examples 3 to 8). FIGS. 19 to 30 show powderXRD spectra of the phthalocyanine crystals of Examples 17 to 22 andComparative Synthetic Examples 3 to 8, respectively. As apparent fromthe powder XRD spectra of FIGS. 19 to 30, any of the phthalocyaninecrystals of Examples 17 to 22 and Comparative Synthetic Examples 3 to 8had a main diffraction peak at Bragg angle (2θ±0.2°) of 27.2° towardCuKα characteristic X-ray (wavelength 1.541 angstrom).

TABLE 6 Aromatic compound to be brought into contact with phthalocyaninecrystal precursor Example 17 2-chloroacetophenone ⁽*⁾ Example 183-chloro-4-fluoroacetophenone ⁽*⁾ Example 19 methyl 2-chlorobenzoate ⁽*⁾Example 20 2,6-dichloroanisole ⁽*⁾ Example 21 2-chlorophenyl acetate ⁽*⁾Example 22 2,4-dichloronitrobenzene ⁽*⁾ Comparative acetophenoneSynthetic Example 3 Comparative methyl 2-methylbenzoate SyntheticExample 4 Comparative anisole Synthetic Example 5 Comparative phenylacetate Synthetic Example 6 Comparative nitrobenzene Synthetic Example 7Comparative 2-fluoronitrobenzene Synthetic Example 8 ⁽*⁾ particularsubstituent-containing aromatic compound

Examples 23 to 25, Comparative Synthetic Examples 9 to 12

As a phthalocyanine crystal precursor, 33 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 3 was added into 90 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe respective aromatic compounds shown in the right column of thefollowing Table 7 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain mixed crystalsof oxytitanium phthalocyanine and metal-free phthalocyanine (they arereferred to as phthalocyanine crystals of Examples 23 to 25 andComparative Synthetic Examples 9 to 12). FIGS. 31 to 37 show powder XRDspectra of the phthalocyanine crystals of Examples 23 to 25 andComparative Synthetic Examples 9 to 12, respectively. As apparent fromthe powder XRD spectra of FIGS. 31 to 37, any of the phthalocyaninecrystals of Examples 23 to 25 and Comparative Synthetic Examples 9 to 12had a main diffraction peak at Bragg angle (2θ±0.2°) of 27.2° towardCuKα characteristic X-ray (wavelength 1.541 angstrom).

TABLE 7 Aromatic compound to be brought into contact with phthalocyaninecrystal precursor Example 23 2-chloroacetophenone ⁽*⁾ Example 242-chloroanisole ⁽*⁾ Example 25 2-chloronitrobenzene ⁽*⁾ Comparativeacetophenone Synthetic Example 9 Comparative anisole Synthetic Example10 Comparative nitrobenzene Synthetic Example 11 Comparative2-fluoronitrobenzene Synthetic Example 12 ⁽*⁾ particularsubstituent-containing aromatic compound

Examples 26 to 34, Comparative Examples 3 to 12

Using phthalocyanine crystals of Examples 17 to 25 and ComparativeSynthetic Examples 3 to 12 as charge generation substances,electrophotographic photoreceptors were produced in accordance with theaforementioned process for producing the photoreceptor (hereinafter,they are optionally referred to as electrophotographic photoreceptors ofExamples 26 to 34 and Comparative Examples 3 to 12). The correspondenceof each electrophotographic photoreceptor to the phthalocyanine crystalused as the charge generation substance was shown in the following Table8 and Table 9.

[Evaluation of Electrophotographic Photoreceptor]

The electrophotographic photoreceptors of Examples 26 to 34 andComparative Examples 3 to 12 were evaluated on electrical properties inthe same manner as the evaluation of Examples 9 to 16. The followingTable 8 and Table 9 show evaluation results of the electrical propertieson the electrophotographic photoreceptors of Examples 26 to 34 andComparative Examples 3 to 12. In the following Table 8 and Table 9,Example(s) and Comparative Example using phthalocyanine crystals eachobtained by bringing an aromatic compound having a similar structureinto contact with a phthalocyanine crystal precursor are shown above andbelow.

TABLE 8 Charge Aromatic compound to Standard- generation be brought intohumidity Electro- substance contact with sensitivity photographic(phthalocyanine phthalocyanine En_(1/2) photoreceptor crystal) crystalprecursor (μJ/cm²) Example 26 Example 17 2-chloroacetophenone ⁽*⁾ 0.081Example 27 Example 18 3-chloro-4- 0.076 fluoroacetophenone ⁽*⁾Comparative Comparative acetophenone 0.089 Example 3 Synthetic Example 3Example 28 Example 19 methyl 2- 0.081 chlorobenzoate ⁽*⁾ ComparativeComparative methyl 2- 0.092 Example 4 Synthetic methylbenzoate Example 4Example 29 Example 20 2,6-dichloroanisole ⁽*⁾ 0.081 ComparativeComparative 1,2- 0.09 Example 5 Synthetic methylenedioxybenzene Example5 Example 30 Example 21 2-chlorophenyl 0.085 acetate ⁽*⁾ ComparativeComparative phenyl acetate 0.094 Example 6 Synthetic Example 6 Example31 Example 22 2,4- 0.079 dichloronitrobenzene ⁽*⁾ ComparativeComparative nitrobenzene 0.101 Example 7 Synthetic Example 7 ComparativeComparative 2-fluoronitrobenzene 0.09 Example 8 Synthetic Example 8 ⁽*⁾particular substituent-containing aromatic compound

TABLE 9 Charge Aromatic compound to Standard- generation be brought intohumidity Electro- substance contact with sensitivity photographic(phthalocyanine phthalocyanine En_(1/2) photoreceptor crystal) crystalprecursor (μJ/cm²) Example 32 Example 23 2-chloroacetophenone ⁽*⁾ 0.087Comparative Comparative acetophenone 0.096 Example 9 Synthetic Example 8Example 33 Example 24 2-chloroanisole ⁽*⁾ 0.101 Comparative Comparative1,2- 0.111 Example 10 Synthetic methylenedioxybenzene Example 10 Example34 Example 25 2-chloronitrobenzene ⁽*⁾ 0.085 Comparative Comparativenitrobenzene 0.104 Example 11 Synthetic Example 11 ComparativeComparative 2-fluoronitrobenzene 0.09 Example 12 Synthetic Example 12⁽*⁾ particular substituent-containing aromatic compound

As apparent from the powder XRD spectra (FIGS. 19 to 37), any of thephthalocyanine crystals of Examples 17 to 25 and Comparative SyntheticExamples 3 to 12 were phthalocyanine crystals having a main diffractionpeak at Bragg angle (2θ±0.2°) of 27.2° toward CuKα characteristic X-ray(wavelength 1.541 angstrom).

These electrophotographic photoreceptors of Examples 26 to 34 andComparative Examples 3 to 12 using the phthalocyanine crystals ofExamples 17 to 25 and Comparative Synthetic Examples 3 to 12 as chargegeneration substances were divided into eight groups (Examples 26, 27and Comparative Example 3; Example 28 and Comparative Example 4; Example29 and Comparative Example 5; Example 30 and Comparative Example 6;Example 31 and Comparative Examples 7, 8; Example 32 and ComparativeExample 9; Example 33 and Comparative Example 10; Example 34 andComparative Example 11, 12) according to the composition of thephthalocyanine crystal used and the structure of the aromatic compoundused in crystal conversion treatment at the production of thephthalocyanine crystal. When Example(s) and Comparative Example(s) arecompared on each group, it is realized that high standard-humiditysensitivity En_(1/2) is obtained in the electrophotographicphotoreceptors of Examples as compared with the electrophotographicphotoreceptors of Comparative Examples.

From the above results, it was evident that high standard-humiditysensitivity En_(1/2) is obtained when the phthalocyanine crystals ofExamples 17 to 25 obtained through a step of converting the crystal formby bringing a phthalocyanine crystal precursor into contact with aparticular substituent-containing aromatic compound (i.e.,phthalocyanine crystals of the invention) were used forelectrophotographic photoreceptors.

Examples 35 to 68, Comparative Synthetic Examples 13 to 14

As a phthalocyanine crystal precursor, 40 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 2 was added into 90 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe contact treatment solutions of Examples 35 to 68 (solutions eachobtained by mixing a particular organic acid compound into a non-acidicorganic compound in a predetermined concentration) shown in thefollowing Table 10 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain crystals eachconsisting of oxytitanium phthalocyanine alone (hereinafter, they areoptionally referred to as phthalocyanine crystals of Examples 35 to 68).

Moreover, the operations the same as in Examples 35 to 68 were carriedout except that contact treatment solutions of Comparative SyntheticExamples 13 and 14 shown in the following Table 11 (solutions eachconsisting of a non-acidic organic compound alone) were used in anamount of 9 ml, respectively instead of the contact treatment solutionsof Examples 35 to 68 to obtain crystals consisting of oxytitaniumphthalocyanine alone (hereinafter, they are optionally referred to asphthalocyanine crystals of Comparative Examples 13 and 14).

Powder XRD spectra of the phthalocyanine crystals of Examples 35 to 68and Comparative Synthetic Examples 13 and 14 were measured. In thepowder XRD spectra obtained, any of the phthalocyanine crystals had amain diffraction peak at Bragg angle (2θ±0.2°) of 27.2° toward CuKαcharacteristic X-ray (wavelength 1.541 angstrom). In this connection,when the non-acidic organic compounds used were the same, powder X-raydiffraction spectra each having about the same shape were obtainedregardless of the presence of the particular organic acid compound. Asrepresentative examples, the powder XRD spectra of the phthalocyaninecrystals of Examples 35, 64, 65, 67, and 68 are shown in FIGS. 38 to 42,respectively.

Example 69

Forty parts by weight of wet cake of the low-crystalline oxytitaniumphthalocyanine (phthalocyanine crystal precursor) obtained in SyntheticExample 2 was added into a solution (a contact treatment solution ofExample 69 shown in the following Table 10) obtained by dissolving 15 gof 3-chlorobenzoic acid (a particular organic acid compound) in 100 mlof tetrahydrofuran (a non-acidic organic compound), followed by stirringat room temperature for 3 hours. After stirring, the product wasfiltrated off and was heated and dried in a vacuum drier to therebyobtain crystals consisting of oxytitanium phthalocyanine alone(hereinafter, they are optionally referred to as phthalocyanine crystalof Example 69). FIG. 43 shows a powder XRD spectrum of thephthalocyanine crystal of Example 69. As apparent from FIG. 43, thephthalocyanine crystal of Example 69 had a main diffraction peak atBragg angle (2θ±0.2°) of 27.2° toward CuKα characteristic X-ray(wavelength 1.541 angstrom).

Comparative Synthetic Example 15

The operations the same as in Example 69 was carried out except that 100ml of tetrahydrofuran was used instead of the tetrahydrofuran solutionof 3-chlorobenzoic acid in the above Example 69, thereby crystalsconsisting of oxytitanium phthalocyanine alone being obtained(hereinafter, they are optionally referred to as phthalocyanine crystalof Comparative Synthetic Example 15). When a powder XRD spectrum wasmeasured on the phthalocyanine crystal of Comparative Synthetic Example15, the resulting powder XRD spectrum had about the same shape as thepowder XRD spectrum (FIG. 43) of the phthalocyanine crystal of the aboveExample 69.

TABLE 10 Contact treatment solution Concentration of particular organicacid Non-acidic organic Particular organic compound compound acidcompound (g/ml) Example 35 3-chlorobenzaldehyde benzoic acid 0.056Example 36 3-chlorobenzaldehyde benzoic acid 0.250 Example 373-chlorobenzaldehyde 3-chlorobenzoic acid 0.018 Example 383-chlorobenzaldehyde 3-chlorobenzoic acid 0.037 Example 393-chlorobenzaldehyde 3-chlorobenzoic acid 0.056 Example 403-chlorobenzaldehyde 3-methoxybenzoic acid 0.056 Example 413-chlorobenzaldehyde 3-methylbenzoic acid 0.056 Example 423-chlorobenzaldehyde 3-nitrobenzoic acid 0.056 Example 433-chlorobenzaldehyde anthranilic acid 0.056 Example 443-chlorobenzaldehyde phthalic acid 0.018 Example 45 3-chlorobenzaldehydetrimellitic acid 0.018 Example 46 3-chlorobenzaldehyde phthalicanhydride 0.056 Example 47 3-chlorobenzaldehyde trimellitic anhydride0.056 Example 48 3-chlorobenzaldehyde pyromellitic anhydride 0.037Example 49 3-chlorobenzaldehyde 2-phenylpropionic acid 0.056 Example 503-chlorobenzaldehyde 1-naphtoic acid 0.056 Example 513-chlorobenzaldehyde 2,6-naphthalenedicarboxylic acid 0.018 Example 523-chlorobenzaldehyde 1,8-naphthalic anhydride 0.037 Example 533-chlorobenzaldehyde 1,2-naphthalic anhydride 0.056 Example 543-chlorobenzaldehyde indole-2-carboxylic acid 0.056 Example 553-chlorobenzaldehyde benzofuran-2-carboxylic acid 0.056 Example 563-chlorobenzaldehyde phenylboronic acid 0.056 Example 573-chlorobenzaldehyde benzenesulfonic acid 0.056 Example 583-chlorobenzaldehyde methyl benzenesulfonate 0.056 Example 593-chlorobenzaldehyde phenyl phosphoric acid 0.056 Example 603-chlorobenzaldehyde phenylphosphonic acid 0.056 Example 613-chlorobenzaldehyde dimethyl phenylphosphonate 0.056 Example 623-chlorobenzaldehyde acetic acid 0.056 Example 63 3-chlorobenzaldehydemethanesulfonic acid 0.056 Example 64 2-chloroacetophenone3-chlorobenzoic acid 0.056 Example 65 2-chloroacetophenone trimelliticanhydride 0.056 Example 66 methyl 2-chlorobenzoate 3-chlorobenzoic acid0.056 Example 67 2,4-dichlorofluorobenzene 3-chlorobenzoic acid 0.056Example 68 2-fluoronitrobenzene 3-chlorobenzoic acid 0.056 Example 69tetrahydrofuran 3-chlorobenzoic acid 0.15 Comparative2,4-dichlorofluorobenzene — — Synthetic Example 13 Comparative2-fluoronitrobenzene — — Synthetic Example 14 Comparativetetrahydrofuran — — Synthetic Example 15

Examples 70 to 74

As a phthalocyanine crystal precursor, 33 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 3 was added into 90 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe contact treatment solutions of Examples 70 to 74 (solutions eachobtained by mixing a particular organic acid compound into a non-acidicorganic compound in a predetermined concentration) shown in thefollowing Table 11 was added thereto, followed by further stirring atroom temperature for 1 hour. After stirring, water was separated and 80parts by weight of methanol was added, followed by stirring and washingat room temperature for 1 hour. After washing, the product was filtratedoff and 80 parts by weight of methanol was again added, followed bystirring and washing for 1 hour. Thereafter, it was filtrated off andwas heated and dried in a vacuum drier to thereby obtain mixed crystalsof oxytitanium phthalocyanine and metal-free phthalocyanine (they arereferred to as phthalocyanine crystals of Examples 70 to 74,respectively).

Powder XRD spectra of the phthalocyanine crystals of Examples 70 to 74were measured. In the powder XRD spectra obtained, any of thephthalocyanine crystals had a main diffraction peak at Bragg angle(2θ±0.2°) of 27.2° toward CuKα characteristic X-ray (wavelength 1.541angstrom). Moreover, powder X-ray diffraction spectra each had about thesame shape. As representative examples, FIG. 44 shows a powder XRDspectrum of the phthalocyanine crystal obtained in Example 70.

TABLE 11 Contact treatment solution Concentration of particular organicacid Non-acidic organic Particular organic compound compound acidcompound (g/ml) Example 70 3-chlorobenzaldehyde 3-chlorobenzoic 0.028acid Example 71 3-chlorobenzaldehyde 3-chlorobenzoic 0.056 acid Example72 3-chlorobenzaldehyde phthalic 0.028 anhydride Example 733-chlorobenzaldehyde trimellitic 0.028 anhydride Example 743-chlorobenzaldehyde pyromellitic 0.028 anhydride

Examples 75 to 114

Using phthalocyanine crystals of Examples 35 to 74 as charge generationsubstances, electrophotographic photoreceptors were produced inaccordance with the aforementioned process for producing thephotoreceptor (hereinafter, they are optionally referred to aselectrophotographic photoreceptors of Examples 75 to 114). Thecorrespondence of each electrophotographic photoreceptor to thephthalocyanine crystal used as the charge generation substance and acomposition thereof was shown in the following Table 12 and Table 13.

[Evaluation of Electrophotographic Photoreceptor]

The electrophotographic photoreceptors of Examples 75 to 114 andComparative Examples 13 to 15 were evaluated on electrical properties inthe same manner as the evaluation of Examples 9 to 16. The followingTable 12 and Table 13 show evaluation results of the sensitivityretention on the electrophotographic photoreceptors of Examples 75 to114 and Comparative Examples 13 to 15. In the following Table 12 andTable 13, Example(s) and Comparative Example using phthalocyaninecrystals each obtained using the same non-acidic organic compound areshown above and below.

TABLE 12 Charge generation Electro- substance Sensitivity photographic(phthalocyanine Non-acidic organic Particular organic acid retentionphotoceptor crystal) compound compound (%) Example 75 Example 353-chlorobenzaldehyde benzoic acid 92.1% Example 76 Example 363-chlorobenzaldehyde benzoic acid 92.0% Example 77 Example 373-chlorobenzaldehyde 3-chlorobenzoic acid 92.3% Example 78 Example 383-chlorobenzaldehyde 3-chlorobenzoic acid 92.1% Example 79 Example 393-chlorobenzaldehyde 3-chlorobenzoic acid 94.3% Example 80 Example 403-chlorobenzaldehyde 3-methoxybenzoic acid 92.6% Example 81 Example 413-chlorobenzaldehyde 3-methylbenzoic acid 92.5% Example 82 Example 423-chlorobenzaldehyde 3-nitrobenzoic acid 94.8% Example 83 Example 433-chlorobenzaldehyde anthranilic acid 93.4% Example 84 Example 443-chlorobenzaldehyde phthalic acid 93.4% Example 85 Example 453-chlorobenzaldehyde trimellitic acid 95.5% Example 86 Example 463-chlorobenzaldehyde phthalic anhydride 94.4% Example 87 Example 473-chlorobenzaldehyde trimellitic anhydride 96.6% Example 88 Example 483-chlorobenzaldehyde pyromellitic anhydride 94.6% Example 89 Example 493-chlorobenzaldehyde 2-phenylpropionic acid 92.0% Example 90 Example 503-chlorobenzaldehyde 1-naphtoic acid 92.6% Example 91 Example 513-chlorobenzaldehyde 2,6-naphthalenedicarboxylic acid 93.4% Example 92Example 52 3-chlorobenzaldehyde 1,8-naphthalic anhydride 92.9% Example93 Example 53 3-chlorobenzaldehyde 1,2-naphthalic anhydride 91.6%Example 94 Example 54 3-chlorobenzaldehyde indole-2-carboxylic acid93.6% Example 95 Example 55 3-chlorobenzaldehyde benzofuran-2-carboxylicacid 92.6% Example 96 Example 56 3-chlorobenzaldehyde phenylboronic acid93.6% Example 97 Example 57 3-chlorobenzaldehyde benzenesulfonic acid94.8% Example 98 Example 58 3-chlorobenzaldehyde methyl benzenesulfonate92.6% Example 99 Example 59 3-chlorobenzaldehyde phenyl phosphoric acid93.7% Example 100 Example 60 3-chlorobenzaldehyde phenylphosphonic acid91.5% Example 101 Example 61 3-chlorobenzaldehyde dimethylphenylphosphonate 91.8% Example 102 Example 62 3-chlorobenzaldehydeacetic acid 91.6% Example 103 Example 63 3-chlorobenzaldehydemethanesulfonic acid 92.6% Example 104 Example 64 2-chloroacetophenone3-chlorobenzoic acid 91.1% Example 105 Example 65 2-chloroacetophenonetrimellitic anhydride 91.1% Example 106 Example 66 methyl2-chlorobenzoate 3-chlorobenzoic acid 90.3% Example 107 Example 672,4-dichlorofluorobenzne 3-chlorobenzoic acid 91.9% ComparativeComparative 2,4-dichlorofluorobenzne — 88.5% Example 13 SyntheticExample 13 Example 108 Example 68 2-fluoronitrobenzene 3-chlorobenzoicacid 93.1% Comparative Comparative 2-fluoronitrobenzene — 90.7% Example14 Synthetic Example 14 Example 109 Example 69 tetrahydrofuran3-chlorobenzoic acid 91.3% Comparative Comparative tetrahydrofuran —89.1% Example 15 Synthetic Example 15

TABLE 13 Charge generation Electro- substance Sensitivity photographic(phthalocyanine Non-acidic organic Particular organic acid retentionphotoreceptor crystal) compound compound (%) Example 110 Example 703-chlorobenzaldehyde 3-chlorobenzoic acid 92.7% Example 111 Example 713-chlorobenzaldehyde 3-chlorobenzoic acid 93.6% Example 112 Example 723-chlorobenzaldehyde phthalic anhydride 92.7% Example 113 Example 733-chlorobenzaldehyde trimellitic anhydride 95.7% Example 114 Example 743-chlorobenzaldehyde pyromellitic anhydride 92.9%

When these electrophotographic photoreceptors of Examples 75 to 114 andComparative Examples 13 to 15 using the phthalocyanine crystals ofExamples 35 to 74 and Comparative Synthetic Examples 13 to 15 as chargegeneration substances were compared, the electrophotographicphotoreceptors of Comparative Examples 14 and 15 were poor instandard-humidity sensitivity En_(1/2) and also poor in sensitivityretention. Moreover, the electrophotographic photoreceptors ofComparative Example 13 had standard-humidity sensitivity En_(1/2) equalto that of the electrophotographic photoreceptors of Examples. However,when the values of the sensitivity retention are compared, theelectrophotographic photoreceptors of Examples using phthalocyaninecrystals obtained by the contact with the non-acidic organic compoundand the particular organic acid compound show little fluctuation insensitivity for a humidity change as compared with theelectrophotographic photoreceptors of Comparative Examples usingphthalocyanine crystals obtained by the contact with the non-acidicorganic compound alone.

Examples 115, 116

An electrophotographic photoreceptor was produced in accordance with theprocedure of the above [Process for Producing Photoreceptor] except that20 parts by weight of the phthalocyanine crystal of Example 1 and 1.25parts by weight of 3-chlorobenzoic acid were used in combination at thepreparation of the coating solution for a charge generation layer in theabove [Process for Producing Photoreceptor] instead of 20 parts byweight of the phthalocyanine crystal of each of the above Examples andComparative Synthetic Examples. Hereinafter, this photoreceptor isoptionally referred to as an electrophotographic photoreceptor ofExample 115.

Moreover, an electrophotographic photoreceptor was produced inaccordance with the procedure the same as in Example 115 except that1.25 parts by weight of trimellitic organic acid anhydride was usedinstead of 1.25 parts by weight of 3-chlorobenzoic acid. Hereinafter,this photoreceptor is optionally referred to as an electrophotographicphotoreceptor of Example 116.

Also on these electrophotographic photoreceptors of Examples 115 and116, electrical properties were evaluated in accordance with theprocedure the same as in the cases of the electrophotographicphotoreceptors of the above Examples 9 to 16 and Comparative Examples 1and 2.

The following Table 14 shows the evaluation results of the electricalproperties on the electrophotographic photoreceptors of Examples 79, 86,115, and 116.

TABLE 14 Additive at preparation of Electro- Charge Non-acidicParticular coating solution Sensitivity photographic generation organicorganic acid for charge retention photoreceptor substance compoundcompound generation layer (%) Example 79 Example 393-chloro-benzaldehyde 3-chloro-benzoic acid — 94.3% Example 86 Example46 phthalic anhydride — 96.6% Example 115 Example 1 — 3-chloro-benzoicacid 90.7% Example 116 Example 1 — trimellitic organic 90.6% acidanhydride

From the above results, it is realized that the effect of improvingsensitivity and suppressing sensitivity fluctuation for a humiditychange in usage environment is small only by adding the aforementionedparticular organic acid compound at the preparation of the coatingsolution for the charge generation layer.

Examples 117 to 131

As a phthalocyanine crystal precursor, 40 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 2 was added into 100 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe contact treatment solutions of Examples 117 to 131 (solutions eachobtained by mixing an electron-withdrawing particular aromatic compoundinto a non-acidic particular organic compound in a predeterminedconcentration) shown in the following Table 15 was added thereto,followed by further stirring at room temperature for 1 hour. Afterstirring, water was separated and 80 parts by weight of methanol wasadded, followed by stirring and washing at room temperature for 1 hour.After washing, the product was filtrated off and 80 parts by weight ofmethanol was again added, followed by stirring and washing for 1 hour.Thereafter, it was filtrated off and was heated and dried in a vacuumdrier to thereby obtain crystals of oxytitanium phthalocyanine alone(hereinafter, they are optionally referred to as phthalocyanine crystalsof Examples 117 to 131).

Powder XRD spectra of the phthalocyanine crystals of Examples 117 to 131were measured. In the powder XRD spectra obtained, any of thephthalocyanine crystals had a main diffraction peak at Bragg angle(2θ±0.2°) of 27.2° toward CuKα characteristic X-ray (wavelength 1.541angstrom). In the case where the non-acidic particular organic compoundsused were the same, powder X-ray diffraction spectra each having aboutthe same shape were obtained regardless of the presence of theelectron-withdrawing particular aromatic compound. As representativeexamples, FIGS. 45 to 48 show powder XRD spectra of the phthalocyaninecrystals obtained in Examples 128 to 131.

Example 132

Forty parts by weight of wet cake of the low-crystalline oxytitaniumphthalocyanine (phthalocyanine crystal precursor) obtained in SyntheticExample 2 was added into a mixed solution (a contact treatment solutionof Example 132 shown in the following Table 15) obtained by dissolving15 g of phthalide (an electron-withdrawing particular aromatic compound)in 100 ml of tetrahydrofuran (a non-acidic particular organic compound),followed by stirring at room temperature for 3 hours. After stirring,the product was filtrated off and was heated and dried in a vacuum drierto thereby obtain crystals consisting of oxytitanium phthalocyaninealone (hereinafter, they are optionally referred to as phthalocyaninecrystal of Example 132). FIG. 49 shows a powder XRD spectrum of thephthalocyanine crystal of Example 132. As apparent from FIG. 49, thepowder XRD spectrum of the phthalocyanine crystal in Example 132 had amain diffraction peak at Bragg angle (2θ±0.2°) of 27.2° toward CuKαcharacteristic X-ray (wavelength 1.541 angstrom).

TABLE 15 Contact treatment solution Concentration ofElectron-withdrawing electron-withdrawing Non-acidic particularparticular aromatic particular aromatic organic compound compoundcompound (g/ml) Example 117 3-chlorobenzaldehyde 3,5-dinitrobenzoic acid0.056 Example 118 3-chlorobenzaldehyde 3-fluorobenzoic acid 0.056Example 119 3-chlorobenzaldehyde phthalide 0.056 Example 1203-chlorobenzaldehyde 2-sulfobenzoic anhydride 0.056 Example 1213-chlorobenzaldehyde 1,3-dinitrobenzne 0.056 Example 1223-chlorobenzaldehyde 4-nitrophthalonitrile 0.056 Example 1233-chlorobenzaldehyde 3-nitroacetophenone 0.056 Example 1243-chlorobenzaldehyde phthalic anhydride 0.056 Example 1253-chlorobenzaldehyde 4-nitrophthalic anhydride 0.056 Example 1263-chlorobenzaldehyde pyromellitic anhydride 0.037 Example 1273-chlorobenzaldehyde 1,8-naphthalic anhydride 0.037 Example 1282,4-dichlorofluorobenzene phthalide 0.056 Example 1292-chloroacetophenone phthalide 0.056 Example 130 methyl 2-chlorobenzoate2-sulfobenzoic acid 0.056 Example 131 2-fluoronitrobenzene2-sulfobenzoic acid 0.056 Example 132 tetrahydrofuran phthalide 0.15

Examples 133 to 136

As a phthalocyanine crystal precursor, 33 parts by weight of wet cake ofthe low-crystalline oxytitanium phthalocyanine obtained in SyntheticExample 3 was added into 90 parts by weight of water, followed bystirring at room temperature for 30 minutes. Thereafter, 9 ml of each ofthe contact treatment solutions of Examples 133 to 136 (solutions eachobtained by mixing an electron-withdrawing particular aromatic compoundinto a non-acidic particular organic compound of 3-chlorobenzaldehyde ina predetermined concentration) shown in the following Table 16 was addedthereto, followed by further stirring at room temperature for 1 hour.After stirring, water was separated and 80 parts by weight of methanolwas added, followed by stirring and washing at room temperature for 1hour. After washing, the product was filtrated off and 80 parts byweight of methanol was again added, followed by stirring and washing for1 hour. Thereafter, it was filtrated off and was heated and dried in avacuum drier to thereby obtain mixed crystals of oxytitaniumphthalocyanine and metal-free phthalocyanine (they are referred to asphthalocyanine crystals of Examples 133 to 136, respectively).

Powder XRD spectra of the phthalocyanine crystals of Examples 133 to 136were measured. In the powder XRD spectra obtained, any of thephthalocyanine crystals had a main diffraction peak at Bragg angle(2θ±0.2°) of 27.2° toward CuKα characteristic X-ray (wavelength 1.541angstrom). Moreover, powder X-ray diffraction spectra each had about thesame shape. As an representative example, FIG. 50 shows a powder XRDspectrum of the phthalocyanine crystal obtained in Example 133.

TABLE 16 Contact treatment solution Concentration ofElectron-withdrawing electron-withdrawing Non-acidic particularparticular aromatic particular aromatic organic compound compoundcompound (g/ml) Example 133 3-chlorobenzaldehyde phthalide 0.028 Example134 3-chlorobenzaldehyde 2-sulfobenzoic anhydride 0.056 Example 1353-chlorobenzaldehyde 4-nitrophthalic anhydride 0.028 Example 1363-chlorobenzaldehyde pyromellitic anhydride 0.028

Examples 137 to 156

Using phthalocyanine crystals of Examples 117 to 136 as chargegeneration substances, electrophotographic photoreceptors were producedin accordance with the above [Process for Producing Photoreceptor](hereinafter, they are optionally referred to as electrophotographicphotoreceptors of Examples 137 to 156). The correspondence of eachelectrophotographic photoreceptor to the phthalocyanine crystal used asthe charge generation substance and a composition thereof was shown inthe following Table 17 and Table 18.

[Evaluation of Electrophotographic Photoreceptor]

The electrophotographic photoreceptors of Examples 137 to 156 andComparative Examples 13 to 15 were evaluated on electrical properties inthe same manner as the evaluation of Examples 9 to 16. The followingTable 17 and Table 18 show evaluation results of the sensitivityretention on the electrophotographic photoreceptors of Examples 137 to156 and Comparative Examples 13 to 15. In the following Table 17 andTable 18, Example(s) and Comparative Example using phthalocyaninecrystals each obtained using the same non-acidic organic compound areshown above and below.

TABLE 17 Charge generation Electro- substance Electron-withdrawingSensitivity photographic (phthalocyanine Non-acidic particularparticular aromatic retention photoreceptor crystal) organic compoundcompound (%) Example 137 Example 117 3-chlorobenzaldehyde3,5-dinitrobenzoic acid 94.7% Example 138 Example 1183-chlorobenzaldehyde 3-fluorobenzoic acid 93.5% Example 139 Example 1193-chlorobenzaldehyde phthalide 92.8% Example 140 Example 1203-chlorobenzaldehyde 2-sulfobenzoic anhydride 93.0% Example 141 Example121 3-chlorobenzaldehyde 1,3-dinitrobenzne 93.3% Example 142 Example 1223-chlorobenzaldehyde 4-nitrophthalonitrile 92.4% Example 143 Example 1233-chlorobenzaldehyde 3-nitroacetophenone 92.6% Example 144 Example 1243-chlorobenzaldehyde phthalic anhydride 94.4% Example 145 Example 1253-chlorobenzaldehyde 4-nitrophthalic anhydride 94.7% Example 146 Example126 3-chlorobenzaldehyde pyromellitic anhydride 94.6% Example 147Example 127 3-chlorobenzaldehyde 1,8-naphthalic anhydride 92.9% Example148 Example 128 2-chloroacetophenone phthalide 88.1% Example 149 Example129 methyl 2-chlorobenzoate 2-sulfobenzoic anhydride 90.3% Example 150Example 130 2,4-dichlorofluorobenzene phthalide 90.2% ComparativeSynthetic 2,4-dichlorofluorobenzene — 88.5% Example 13 ComparativeExample 13 Example 151 Example 131 2-fluoronitrobenzene 2-sulfobenzoicanhydride 91.9% Comparative Synthetic 2-fluoronitrobenzene — 90.7%Example 14 Comparative Example 14 Example 152 Example 132tetrahydrofuran phthalide 91.1% Comparative Synthetic tetrahydrofuran —89.1% Example 15 Comparative Example 15

TABLE 18 Charge generation Electro- substance Electron-withdrawingSensitivity photographic (phthalocyanine Non-acidic particularparticular aromatic retention photoreceptor crystal) organic compoundcompound (%) Example 153 Example 133 3-chlorobenzaldehyde phthalide90.8% Example 154 Example 134 3-chlorobenzaldehyde 2-sulfobenzoicanhydride 91.1% Example 155 Example 135 3-chlorobenzaldehyde4-nitrophthalic anhydride 92.2% Example 156 Example 1363-chlorobenzaldehyde pyromellitic anhydride 92.9%

When these electrophotographic photoreceptors of Examples 137 to 156 andComparative Examples 13 to 15 using the phthalocyanine crystals ofExamples 117 to 136 and Comparative Synthetic Examples 13 to 15 ascharge generation substances were compared, the electrophotographicphotoreceptors of Comparative Examples 14 and 15 were poor instandard-humidity sensitivity En_(1/2). The electrophotographicphotoreceptors of Comparative Example 13 had standard-humiditysensitivity En_(1/2) equal to that of the electrophotographicphotoreceptors of Examples. However, when the values of the sensitivityretention are compared, the electrophotographic photoreceptors ofExamples using phthalocyanine crystals obtained by the contact with thenon-acidic particular organic compound and the electron-withdrawingparticular aromatic compound show little fluctuation in sensitivity fora humidity change as compared with the electrophotographicphotoreceptors of Comparative Examples using phthalocyanine crystalsobtained by the contact with the non-acidic particular organic compoundalone.

Examples 157, 158

An electrophotographic photoreceptor was produced in accordance with theprocedure of the above [Process for Producing Photoreceptor] except that20 parts by weight of the phthalocyanine crystal of Example 1 and 1.25parts by weight of phthalide were used in combination in thefine-dispersion treatment step at the preparation of the coatingsolution for a charge generation layer in the above [Process forProducing Photoreceptor]. Hereinafter, this photoreceptor is optionallyreferred to as an electrophotographic photoreceptor of Example 157.

Moreover, an electrophotographic photoreceptor was produced inaccordance with the procedure the same as in Example 157 except that1.25 parts by weight of 2-sulfobenzoic anhydride was used instead of1.25 parts by weight of phthalide. Hereinafter, this photoreceptor isoptionally referred to as an electrophotographic photoreceptor ofExample 158.

On these electrophotographic photoreceptors of Examples 157 and 158,electrical properties were also evaluated in accordance with theprocedure the same as in the cases of the electrophotographicphotoreceptors of the above Examples 9 to 16. The following Table 19shows the evaluation results.

TABLE 19 Contact solution Additive at Non-acidic Electron- preparationof Electro- Charge particular withdrawing coating solution Sensitivityphotographic generation organic particular for charge retentionphotoreceptor substance compound aromatic compound generation layer (%)Example 139 Example 119 3-chloro- phthalide — 92.8% benzaldehyde Example140 Example 120 2-sulfobenzoic — 93.0% anhydride Example 157 Example 1 —phthalide 90.7% Example 158 Example 1 — 2-sulfobenzoic 90.6% anhydride

From the above results, it was realized that the above effect (effect ofimproving sensitivity and suppressing sensitivity fluctuation for ahumidity change in usage environment) is small by sole addition of theaforementioned electron-withdrawing particular aromatic compound at thepreparation of the coating solution for the charge generation layer.

Example 159

An aluminum cylinder made of aluminum alloy which has an outer diameterof 30 mm, a length of 350 mm, and a wall thickness of 1.0 mm and whosesurface had been roughly cut (Rmax=1.2) was subjected to anodicoxidation and then to sealing treatment with a sealing agent containingnickel acetate as a main component, whereby an anodic oxidation film(almite film) of about 6 μm was formed.

The cylinder was dip-coated with the coating solution for chargegeneration layer previously prepared in Example 87 to thereby form acharge generation layer in such a manner that the film thickness afterdrying was 0.4 μm. Subsequently, 100 parts by weight of a polycarbonateresin (viscosity-average molecular weight: 49,200) having a terminalstructural formula derived from p-t-butylphenol and comprising 51% bymol of a repeating unit represented by the above structural formula (G)and 49% by mol of a repeating unit represented by the above structuralformula (H), 50 parts by weight of a mixture consisting of a compoundgroup of geometric isomers having a structure represented by the aboveformula (F), 8 parts by weight of BHT (3,5-di-t-butyl-4-hydroxytoluene)as an antioxidant, and 0.05 part by weight of silicone oil as a levelingagent were mixed with 640 parts by weight of a mixed solvent oftetrahydrofuran and toluene (80% by weight of tetrahydrofuran and 20% byweight of toluene) to prepare a coating solution for charge transportlayer. The above-produced cylinder having the charge generation layerthereon was dip-coated with the coating solution for charge transportlayer to form a charge transport layer having a film thickness of 35 μmafter drying, whereby an electrophotographic photoreceptor was produced.This photoreceptor is referred to as an electrophotographicphotoreceptor of Example 159.

Example 160

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 160.

Example 161

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 161.

Example 162

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 162.

Example 163

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 163.

Example 164

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 105 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 164.

Example 165

An electrophotographic photoreceptor was produced in the same manner asin Example 164 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 165.

Example 166

An electrophotographic photoreceptor was produced in the same manner asin Example 164 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 166.

Example 167

An electrophotographic photoreceptor was produced in the same manner asin Example 164 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 167.

Example 168

An electrophotographic photoreceptor was produced in the same manner asin Example 164 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 168.

Example 169

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 97 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 169.

Example 170

An electrophotographic photoreceptor was produced in the same manner asin Example 169 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 170.

Example 171

An electrophotographic photoreceptor was produced in the same manner asin Example 169 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 171.

Example 172

An electrophotographic photoreceptor was produced in the same manner asin Example 169 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 172.

Example 173

An electrophotographic photoreceptor was produced in the same manner asin Example 169 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 173.

Example 174

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 79 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 174.

Example 175

An electrophotographic photoreceptor was produced in the same manner asin Example 174 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 175.

Example 176

An electrophotographic photoreceptor was produced in the same manner asin Example 174 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 176.

Example 177

An electrophotographic photoreceptor was produced in the same manner asin Example 174 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 177.

Example 178

An electrophotographic photoreceptor was produced in the same manner asin Example 174 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 178.

Example 179

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 145 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 179.

Example 180

An electrophotographic photoreceptor was produced in the same manner asin Example 179 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 180.

Example 181

An electrophotographic photoreceptor was produced in the same manner asin Example 179 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 181.

Example 182

An electrophotographic photoreceptor was produced in the same manner asin Example 179 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 182.

Example 183

An electrophotographic photoreceptor was produced in the same manner asin Example 179 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 183.

Example 184

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 144 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 184.

Example 185

An electrophotographic photoreceptor was produced in the same manner asin Example 184 except that the film thickness of the charge transportlayer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 185.

Example 186

An electrophotographic photoreceptor was produced in the same manner asin Example 184 except that the film thickness of the charge transportlayer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 186.

Example 187

An electrophotographic photoreceptor was produced in the same manner asin Example 184 except that the film thickness of the charge transportlayer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 187.

Example 188

An electrophotographic photoreceptor was produced in the same manner asin Example 184 except that the film thickness of the charge transportlayer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Example 188.

Example 189

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 9 was used instead of the coating solution forcharge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 189.

Example 190

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Example 26 was used instead of the coating solutionfor charge generation layer used in Example 159. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 190.

Comparative Example 16

An electrophotographic photoreceptor was produced in the same manner asin Example 159 except that the coating solution for charge generationlayer prepared in Comparative Example 15 was used instead of the coatingsolution for charge generation layer used in Example 159. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofComparative Example 16.

Comparative Example 17

An electrophotographic photoreceptor was produced in the same manner asin Comparative Example 16 except that the film thickness of the chargetransport layer was 30 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Comparative Example 17.

Comparative Example 18

An electrophotographic photoreceptor was produced in the same manner asin Comparative Example 16 except that the film thickness of the chargetransport layer was 25 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Comparative Example 18.

Comparative Example 19

An electrophotographic photoreceptor was produced in the same manner asin Comparative Example 16 except that the film thickness of the chargetransport layer was 20 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Comparative Example 19.

Comparative Example 20

An electrophotographic photoreceptor was produced in the same manner asin Comparative Example 16 except that the film thickness of the chargetransport layer was 15 μm. This photoreceptor is referred to as anelectrophotographic photoreceptor of Comparative Example 20.

[Evaluation of Electrophotographic Photoreceptor]

The half-decay exposure E1/2 of the electrophotographic photoreceptorsobtained in Examples 159 to 190 and Comparative Examples 16 to 20 wasmeasured using a commercially available photoreceptor-evaluatingapparatus (Cynthia 55 manufactured by Gentec Co.) in a static mode inaccordance with the procedure illustrated in the following.

A charging device was disposed at an angle of 0°, an exposing device anda surface potentiometer probe at an angle of 90°, and an erasing deviceat an angle of 270° C. The charging device, surface potentiometer probe,and erasing device were disposed so that the distance from thephotoreceptor surface is 2 mm. The photoreceptor after having beenallowed to stand in environment of a temperature of 25° C.±2° C. andrelative humidity of 50% rh±5 for 8 hours was electrically charged in adark place by being passed at a constant rotation speed (30 rpm) on ascorotron charging device, which was set in such a manner that theelectrical discharge was carried out so that the surface potential ofthe photoreceptor was adjusted to be about −700 V.

When the photoreceptor surface after electrical charging reached theprobe position, it was stopped and, 2.5 seconds after it was stopped, itwas irradiated with monochromatic light of 780 nm in the intensity of0.15 μW/cm² for 7.5 seconds obtained from an annexed spectral lightsource system POLAS34. The exposure required for decreasing the surfacepotential of the photoreceptor from −550 V to −275 V was measured. Afterthe photoreceptor was again rotated and full arc erase was conductedwith an erasing device, the same operations were carried out. The cyclewas repeated six times and the measured values of the exposure obtainedin 5 cycles excluding first cycle were averaged and the resultingaverage value was determined as half-decay exposure E1/2 (μJ/cm²). Themeasured results were shown in Table 20.

Then, the photoreceptor was mounted on an electrophotographicproperty-evaluating apparatus, which was manufactured according to thestandard of the Society of Electrophotography [“Zoku DenshishashinGijutsu No Kiso To Oyo”, edited by the Society of Electrophotography,issued by Corona Publishing Co. Ltd, pp. 404-405] and electricalproperties were evaluated through a cycle of charging, exposure,measurement of potential, and erase.

A charging device was disposed at an angle of −70°, an exposing deviceat an angle of 0° C., a surface potentiometer probe at an angle of 36°,and an erasing device at an angle of −150° C. Individual devices weredisposed so that the distance from the photoreceptor surface is 2 mm.For the charging, a scorotron charging device is used. As an exposinglamp, a halogen lamp JDR110V-85WLN/K7 manufactured by Ushio, Inc. wasused and monochromatic light of 780 nm is formed using a filter MX0780manufactured by Asahi Spectra Co., Ltd. LED light of 660 nm was used asan erasing light.

The photoreceptor after having been allowed to stand in environment of atemperature of 25° C.±2° C. and relative humidity of 50% rh±5% for 8hours was charged with rotation at a constant rotation speed (60 rpm) sothat an initial surface potential of the photoreceptor was −700 V. Whenthe charged photoreceptor surface passed through an exposure portionirradiated with monochromatic light of 780 nm and reached the probeposition, the surface potential was measured (time for exposure topotential measurement: 100 ms).

The monochromatic light of 780 nm was passed through ND filter to changelight intensity, the photoreceptor was irradiated with a light in anexposure 0 to 10 times the half-decay exposure E_(1/2), and surfacepotential was measured at each exposure. The operations were carried outunder the environment of a temperature of 25° C.±2° C. and a relativehumidity of 50% rh±5% (normal temperature and normal humidityenvironment; hereinafter suitably sometimes referred to as “NNenvironment”) and potential after exposure under the NN environment ateach exposure (hereinafter suitably sometimes referred to as “V_(NN)”)was measured.

Thereafter, after the photoreceptor had been allowed to stand in theenvironment of a temperature of 25° C.±2° C. and relative humidity of10% rh±5%, the same operations are carried out in the environment of atemperature of 25° C.±2° C. and a humidity of 10% rh±5% (hereinaftersometimes referred to as “NL environment”) and potential after exposureunder the NL environment at each exposure (hereinafter sometimesreferred to as “V_(NL)”) was measured.

An absolute value of the difference between potential after exposureV_(NN) under the NN environment and V_(NL) under the NL environment atthe same exposure (|V_(NN)−V_(NL)|) was calculated and the maximum valuewas determined as environmental fluctuation dependence, the value beingshown in the following Table 20.

Moreover, images formed using the electrophotographic photoreceptor wereevaluated by the following evaluation method.

The electrophotographic photoreceptor was mounted on the cartridge for adigital copying machine DIALTA Di350 manufactured by Minolta Co. andthen the cartridge was mounted on the copying machine. After the copyingmachine was allowed to stand under the environment of a temperature of35° C.±2° C. and relative humidity of 83% rh±5% for 24 hours and thenfurther allowed to stand under the environment of a temperature of 5°C.±2° C. and relative humidity of 10% rh±5% for 5 hours, halftone imageswere printed.

At that time, the occurrence of black streaks generated through oneround of the electrophotographic photoreceptor was compared. The copyingmachine manufactured by Minolta Co. is an apparatus wherein anelectrophotographic photoreceptor is charged by a scorotron chargingdevice and developed in a two-component contact developing method andhence black streaks tend to occur.

TABLE 20 Half-decay Environmental Film exposure fluctuation thickness E½dependence Image Solvent Additive (μm) (μJ/cm²) (V) evaluation Example159 3-chlorobenzaldehyde Trimellitic 35 0.049 20 ⊚ acid Example 1603-chlorobenzaldehyde Trimellitic 30 0.051 18 ⊚ acid Example 1613-chlorobenzaldehyde Trimellitic 25 0.055 20 ⊚ acid Example 1623-chlorobenzaldehyde Trimellitic 20 0.066 17 ⊚ acid Example 1633-chlorobenzaldehyde Trimellitic 15 0.075 16 ⊚ acid Example 1642-chloro- Trimellitic 35 0.053 19 ⊚ acetophenone acid Example 1652-chloro- Trimellitic 30 0.057 20 ⊚ acetophenone acid Example 1662-chloro- Trimellitic 25 0.060 18 ⊚ acetophenone acid Example 1672-chloro- Trimellitic 20 0.069 16 ⊚ acetophenone acid Example 1682-chloro- Trimellitic 15 0.078 15 ⊚ acetophenone acid Example 1693-chlorobenzaldehyde benzene- 35 0.048 19 ⊚ sulfonic acid Example 1703-chlorobenzaldehyde benzene- 30 0.050 19 ⊚ sulfonic acid Example 1713-chlorobenzaldehyde benzene- 25 0.053 19 ⊚ sulfonic acid Example 1723-chlorobenzaldehyde benzene- 20 0.064 17 ⊚ sulfonic acid Example 1733-chlorobenzaldehyde benzene- 15 0.074 15 ⊚ sulfonic acid Example 1743-chlorobenzaldehyde 3-chloro- 35 0.050 30 ⊚ benzoic acid Example 1753-chlorobenzaldehyde 3-chloro- 30 0.052 30 ⊚ benzoic acid Example 1763-chlorobenzaldehyde 3-chloro- 25 0.056 29 ⊚ benzoic acid Example 1773-chlorobenzaldehyde 3-chloro- 20 0.068 27 ⊚ benzoic acid Example 1783-chlorobenzaldehyde 3-chloro- 15 0.077 26 ⊚ benzoic acid Example 1793-chlorobenzaldehyde 4-nitro- 35 0.048 28 ⊚ phthalic anhydride Example180 3-chlorobenzaldehyde 4-nitro- 30 0.051 29 ⊚ phthalic anhydride* The occurrence of black streaks observed at the image evaluation bythe above-defined procedure is shown by the following symbols.

-   ⊚: black streaks are entirely not observed-   ◯: black streaks are hardly observed-   Δ: black streaks are slightly observed-   x: black streaks are clearly observed

TABLE 21 Half-decay Environmental Film exposure fluctuation thickness E½dependence Image Solvent Additive (μm) (μJ/cm²) (V) evaluation Example181 3-chlorobenz- 4-nitro-phthalic 25 0.056 26 ⊚ aldehyde anhydrideExample 182 3-chlorobenz- 4-nitro-phthalic 20 0.066 25 ⊚ aldehydeanhydride Example 183 3-chlorobenz- 4-nitro-phthalic 15 0.076 23 ⊚aldehyde anhydride Example 184 3-chlorobenz- phthalic 35 0.050 30 ⊚aldehyde anhydride Example 185 3-chlorobenz- phthalic 30 0.053 29 ⊚aldehyde anhydride Example 186 3-chlorobenz- phthalic 25 0.056 30 ⊚aldehyde anhydride Example 187 3-chlorobenz- phthalic 20 0.067 29 ⊚aldehyde anhydride Example 188 3-chlorobenz- phthalic 15 0.078 27 ⊚aldehyde anhydride Example 189 3-chlorobenz- none 25 0.058 34 ◯ aldehydeExample 190 2-chloro- none 25 0.061 35 ◯ acetophenone Comparativetetrahydro- none 35 0.052 55 X Example 16 furan Comparative tetrahydro-none 30 0.054 50 X Example 17 furan Comparative tetrahydro- none 250.059 49 X Example 18 furan Comparative tetrahydro- none 20 0.070 47 XExample 19 furan Comparative tetrahydro- none 15 0.078 42 Δ Example 20furan* The occurrence of black streaks observed at the image evaluation bythe above-defined procedure is shown by the following symbols.

-   ⊚: black streaks are entirely not observed-   ◯: black streaks are hardly observed-   Δ: black streaks are slightly observed-   x: black streaks are clearly observed

From the results of Table 20, the following are found. When compared atthe same film thickness, the electrophotographic photoreceptors ofExamples 159 to 190 have smaller half-decay exposure E1/2 and highersensitivity and also smaller environmental fluctuation dependence thanthe photoreceptors of Comparative Examples have. When images were formedby an image-forming device in a contact development mode on which theseelectrophotographic photoreceptors were mounted and the image propertieswere evaluated, black streaks were observed in the case of thephotoreceptors of Comparative Examples, while no black streaks wereobserved in the case of the electrophotographic photoreceptors of theinvention.

From the above, it is evident that the electrophotographicphotoreceptors of Examples 159 to 190 are highly sensitive and less influctuation of properties for a humidity change and a process cartridgeand an image-forming device on which these electrophotographicphotoreceptors are mounted can provide high quality images without imagedefects for a environment change.

Example 191

One hundred parts by weight of a polycarbonate resin having a terminalstructural formula derived from p-t-butylphenol consisting of 51% by molof a repeating unit represented by the above structural formula (G) and49% by mol of a repeating unit represented by the above structuralformula (H), 50 parts by weight of a charge transport substancerepresented by the following structural formula (I), and 0.05 part byweight of silicone oil were mixed with 640 parts by weight of a mixedsolvent of tetrahydrofuran and toluene in a ratio of 8:2 to prepare acoating solution for charge transport layer.

An electrophotographic photoreceptor was produced in the same manner asin Example 9 except that the coating solution for charge transport layerprepared by the above method was used instead of the coating solutionfor charge transport layer used in Example 9. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 191.

Example 192

An electrophotographic photoreceptor was produced in the same manner asin Example 191 except that the compound represented by the followingstructural formula (J) was used instead of the compound represented bythe following structural formula (I) used in Example 191. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofExample 192.

Example 193

An electrophotographic photoreceptor was produced in the same manner asin Example 191 except that the compound represented by the followingstructural formula (K) was used instead of the compound represented bythe structural formula (I) used in Example 191. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 193.

Example 194

An electrophotographic photoreceptor was produced in the same manner asin Example 191 except that a mixture of the compounds represented by thefollowing structural formulae (L) and (M) in a ratio of L/M=1/1 (byweight) were used instead of the compound represented by the structuralformula (I) used in Example 191 so that the total weight was the same asthe weight of the compound of the structural formula (I) used in Example191 as well as the coating solution for charge generation layer used inExample 87 was used instead of the coating solution for chargegeneration layer used in Example 9. This photoreceptor is referred to asan electrophotographic photoreceptor of Example 194.

Example 195

An electrophotographic photoreceptor was produced in the same manner asin Example 194 except that a mixture of the compounds represented by thefollowing structural formulae (N) and (O) in a ratio of N/O=1/1 (byweight) was used instead of the compounds represented by the structuralformulae (L) and (M) used in Example 194. This photoreceptor is referredto as an electrophotographic photoreceptor of Example 195.

Example 196

An electrophotographic photoreceptor was produced in the same manner asin Example 194 except that the compound represented by the followingstructural formula (P) was used in the same amount as the total weightof the mixture of the structural formulae (L) and (M) instead of themixture of the structural formulae (L) and (M) used in Example 194. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofExample 196.

Example 197

An electrophotographic photoreceptor was produced in the same manner asin Example 196 except that a polycarbonate resin consisting of therepeating structural unit represented by the following structuralformula (Q) was used instead of the polycarbonate resin used for thecoating solution for charge transport layer in Example 196. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofExample 197.

Example 198

An electrophotographic photoreceptor was produced in the same manner asin Example 196 except that a binder resin consisting of the repeatingstructural unit represented by the following structural formula (R) wasused instead of the polycarbonate resin used for the coating solutionfor charge transport layer and a mixture consisting of the compoundgroup of geometric isomers containing a structure represented by theabove structural formula (F) as a main component was used instead of thecompound represented by the above structural formula (P) in Example 196.This photoreceptor is referred to as an electrophotographicphotoreceptor of Example 198.

Example 199

An electrophotographic photoreceptor was produced in the same manner asin Example 198 except that a binder resin consisting of the repeatingstructural unit represented by the following structural formula (S) wasused instead of the binder resin consisting of the repeating structuralunit represented by the structural formula (R) used in Example 198 andthe coating solution for charge transport layer used in Example 79 wasused as a coating solution for charge transport layer. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofExample 199.

Example 200

An electrophotographic photoreceptor was produced in the same manner asin Example 198 except that a polycarbonate resin consisting of therepeating structural unit represented by the following structuralformula (T) was used instead of the binder resin used for the coatingsolution for charge transport layer in Example 198. This photoreceptoris referred to as an electrophotographic photoreceptor of Example 200.

Example 201

An electrophotographic photoreceptor was produced in the same manner asin Example 198 except that the coating solution for charge generationlayer used in Example 97 was used instead of the coating solution forcharge generation layer used in Example 198 and a binder resinconsisting of the repeating structural unit represented by the followingstructural formula (U) was used as a binder resin for the coatingsolution for charge transport layer. This photoreceptor is referred toas an electrophotographic photoreceptor of Example 201.

Example 202

An electrophotographic photoreceptor was produced in the same manner asin Example 198 except that a binder resin consisting of the repeatingstructural unit represented by the following structural formula (V) wasused instead of the binder resin used for the coating solution forcharge transport layer used in Example 201. This photoreceptor isreferred to as an electrophotographic photoreceptor of Example 202.

Comparative Example 21

An electrophotographic photoreceptor was produced in the same manner asin Example 191 except that the charge generation substance for thecoating solution for charge generation layer was changed to the compoundobtained in Comparative Synthetic Example 1. This photoreceptor isreferred to as an electrophotographic photoreceptor of ComparativeExample 21.

Comparative Example 22

An electrophotographic photoreceptor was produced in the same manner asin Example 192 except that the charge generation substance for thecoating solution for charge generation layer was changed to the compoundobtained in Comparative Synthetic Example 1. This photoreceptor isreferred to as an electrophotographic photoreceptor of ComparativeExample 22.

<Measurement of Properties of Electrophotographic Photoreceptor>

On the electrophotographic photoreceptors produced in Examples 191 to202 and Comparative Examples 21 to 22, standard-humidity sensitivityEn_(1/2) and low-humidity sensitivity El_(1/2) were measured inaccordance with the same procedure as in the case of theelectrophotographic photoreceptors of Examples 9 to 16 and thesensitivity retention (%) for a humidity change was determined. Theresults are shown in the following Table 22.

TABLE 22 Charge generation Electro- substance Sensitivity photographic(phthalocyanine Non-acidic organic Particular organic acid retentionphotoreceptor crystal) compound compound (%) Example 191 Example 13-chlorobenzaldehyde none 93.1 Example 192 Example 13-chlorobenzaldehyde none 93.2 Example 193 Example 13-chlorobenzaldehyde none 93.6 Example 194 Example 473-chlorobenzaldehyde trimellitic anhydride 93.6 Example 195 Example 473-chlorobenzaldehyde trimellitic anhydride 98.7 Example 196 Example 473-chlorobenzaldehyde trimellitic anhydride 95.8 Example 197 Example 473-chlorobenzaldehyde trimellitic anhydride 95.9 Example 198 Example 473-chlorobenzaldehyde trimellitic anhydride 95.2 Example 199 Example 393-chlorobenzaldehyde 3-chlorobenzoic acid 90.8 Example 200 Example 393-chlorobenzaldehyde 3-chlorobenzoic acid 89.7 Example 201 Example 573-chlorobenzaldehyde benzenesulfonic acid 91.1 Example 202 Example 573-chlorobenzaldehyde benzenesulfonic acid 92.0 Comparative Comparativeo-dichlorobenzene none 85.3 Example 21 Synthetic Example 1 ComparativeComparative o-dichlorobenzene none 85.3 Example 22 Synthetic Example 1

Example 203

An aluminum cylinder made of aluminum which had an outer diameter of 30mm, a length of 376 mm, and a wall thickness of 0.75 mm and whosesurface had been mirror-finished was subjected to anodic oxidation andthen to sealing treatment with a sealing agent containing nickel acetateas a main component, whereby an anodic oxidation film (almite film) ofabout 6 μm was formed. The cylinder was dip-coated with the coatingsolution for charge generation layer previously prepared in Example 87to thereby form a charge generation layer in such a manner that the filmthickness after drying became 0.4 μm.

Subsequently, 50 parts by weight of a mixture consisting of a compoundgroup of geometric isomers containing a structure represented by theabove structural formula (F) as a main component, 100 parts by weight ofa polycarbonate resin (viscosity-average molecular weight: 49,200)having a terminal structural formula derived from p-t-butylphenol andcomprising 51% by mol of a repeating unit represented by the abovestructural formula (G) and 49% by mol of a repeating unit represented bythe above structural formula (H), 8 parts by weight of3,5-di-t-butyl-4-hydroxytoluene as an antioxidant, and 0.05 part byweight of silicone oil as a leveling agent were mixed with 640 parts byweight of a mixed solvent of tetrahydrofuran and toluene (80% by weightof tetrahydrofuran and 20% by weight of toluene) to prepare a coatingsolution for charge transport layer.

The above-produced cylinder having the charge generation layer thereonwas dip-coated with the coating solution for charge transport layer toform a charge transport layer having a film thickness of 18 μm afterdrying, whereby an electrophotographic photoreceptor was produced. Thisphotoreceptor is referred to as an electrophotographic photoreceptor ofExample 203.

Example 204

An electrophotographic photoreceptor was produced in the same manner asin Example 203 except that the coating solution for charge generationlayer used in Example 203 was changed to the coating solution for chargegeneration layer prepared in Example 105. This photoreceptor is referredto as an electrophotographic photoreceptor of Example 204.

Comparative Example 23

An electrophotographic photoreceptor was produced in the same manner asin Example 203 except that the coating solution for charge generationlayer used in Example 203 was changed to the coating solution for chargegeneration layer prepared in Comparative Example 15.

<Production of Toner for Development>

Preparation of Wax/Long-Chain Polymerizable Monomer Dispersion Liquid A1

Twenty-seven parts (540 g) of paraffin wax (HNP-9 manufactured by NipponSeiro Co., Ltd., surface tension 23.5 mN/m, melting point 82° C.,melting calorie 220 J/g, melt peak half bandwidth 8.2° C., crystallizedpeak half bandwidth 13.0° C.), 2.8 parts by weight of stearyl acrylate(manufactured by Tokyo Chemical Industry Co., Ltd.), 1.9 parts by weightof an aqueous solution of 20% by weight of sodiumdodecylbenzenesulfonate (Neogen S20A manufactured by Dai-Ichi KogyoSeiyaku Co., Ltd., hereinafter, optionally abbreviated as “20% aqueousDBS solution”), and 68.3 parts of demineralized water were heated to 90°C. and stirred at a round number of 8000 rpm in a homomixer (Mark II fmodel manufactured by Tokusyu Kika Kogyo Co.) for 10 minutes.

Then, the dispersion liquid was heated to 90° C. and circulationemulsification was started under a pressurized condition of about 25 MPausing a homogenizer (15-M-8PA type manufactured by Golin Co.) to effectdispersion under measurement by means of microtrack UPA manufactured byNikkiso Co., Ltd. (hereinafter, optionally abbreviated as “microtrackUPA”) so as to achieve a volume-average particle size of 250 nm, wherebya wax/long-chain polymerizable monomer dispersion liquid A1 (emulsionsolid matter concentration=30.2% by weight) was prepared.

Preparation of Silicone Wax Dispersion Liquid A2

Twenty-seven parts (540 g) of alkyl-modified silicone wax (melting point72° C.), 1.9 parts by weight of 20% aqueous DBS solution, and 71.1 partsof demineralized water were placed in a 3 L stainless steel vessel,heated to 90° C., and stirred at a round number of 8000 rpm in ahomomixer (Mark II f model manufactured by Tokusyu Kika Kogyo Co.) for10 minutes.

Then, the dispersion liquid was heated to 99° C. and circulationemulsification was started under a pressurized condition of about 45 MPausing a homogenizer (15-M-8PA type manufactured by Golin Co.) to effectdispersion under measurement by means of microtrack UPA so as to achievevolume-average particle size of 240 nm, whereby a silicone waxdispersion liquid A2 (emulsion solid matter concentration=27.4% byweight) was prepared.

Preparation of Polymer Primary Particle Dispersion Liquid A1

Into a reaction vessel (inner volume 21 L, inner diameter 250 mm, height420 mm) fitted with a stirring apparatus (three blades), aheating/cooling apparatus, a concentrating apparatus, and amaterial/auxiliary charging apparatus were charged 35.6 parts by weight(712.12 g) of the wax/long-chain polymerizable monomer dispersion liquidA1 and 259 parts of demineralized water, and the whole was heated to 90°C. under stirring at a rotation number of 103 rpm under a nitrogenstream.

Then, a mixture of the following monomers and aqueous emulsifiersolution was added thereto over a period of 5 hours from the initiationof polymerization. The time when the addition of the mixture of themonomers and aqueous emulsifier solution was started was regarded as theinitiation of polymerization. The following aqueous initiator solutionwas added over a period of 4.5 hours from 30 minutes after theinitiation of polymerization. Furthermore, the following additionalaqueous initiator solution was added over a period of 2 hours from 5hours after the initiation of polymerization and the whole was furtherkept at a round number of 103 rpm and an inner temperature of 90° C. for1 hour.

[Monomers] Styrene 76.8 parts (1535.0 g) Butyl acrylate 23.2 partsAcrylic acid 1.5 parts Trichlorobromomethane 1.0 part Hexanedioldiacrylate 0.7 part [Aqueous Emulsifier Solution] 20% aqueous DBSsolution 1.0 part Demineralized water 67.1 parts [Aqueous InitiatorSolution] 8% aqueous hydrogen peroxide solution 15.5 parts 8% aqueousL(+)-ascorbic acid solution 15.5 parts [Additional Aqueous InitiatorSolution] 8% aqueous L(+)-ascorbic acid solution 14.2 parts

After the polymerization was finished, the whole was cooled to obtain amilk-white polymer primary particle dispersion liquid A1. Thevolume-average particle size measured by means of microtrack UPA was 280nm and the solid matter concentration was 21.1% by weight.

Preparation of Polymer Primary Particle Dispersion Liquid A2

Into a reaction vessel (inner volume 21 L, inner diameter 250 mm, height420 mm) fitted with a stirring apparatus (three blades), aheating/cooling apparatus, a concentrating apparatus, and amaterial/auxiliary charging apparatus were charged 23.6 parts by weight(472.3 g) of the silicone wax dispersion liquid A2, 1.5 parts by weightof 20% aqueous DBS solution, and 324 parts of demineralized water, andthe whole was heated to 90° C. under a nitrogen stream and 3.2 parts byweight of an 8% aqueous hydrogen peroxide solution and 3.2 parts byweight of an 8% aqueous L(+)-ascorbic acid solution were added at onceunder stirring at 103 rpm.

After 5 minutes, a mixture of the following monomers and aqueousemulsifier solution was added thereto over a period of 5 hours from theinitiation of polymerization (after 5 minutes from the time when themixture of 3.2 parts by weight of an 8% aqueous hydrogen peroxidesolution and 3.2 parts by weight of an 8% aqueous L(+)-ascorbic acidsolution were added at once). The following aqueous initiator solutionwas added over a period of 6 hours from the initiation ofpolymerization. Furthermore, the whole was kept at a round number of 103rpm and an inner temperature of 90° C. for 1 hour.

[Monomers] Styrene 92.5 parts (1850.0 g) Butyl acrylate 7.5 partsAcrylic acid 1.5 parts Trichlorobromomethane 0.6 part [AqueousEmulsifier Solution] 20% aqueous DBS solution 1.5 part Demineralizedwater 66.2 parts [Aqueous Initiator Solution] 8% aqueous hydrogenperoxide solution 18.9 parts 8% aqueous L(+)-ascorbic acid solution 18.9parts

After the polymerization was finished, the whole was cooled to obtain amilk-white polymer primary particle dispersion liquid A2. Thevolume-average particle size measured by means of microtrack UPA was 290nm and the solid matter concentration was 19.0% by weight.

Preparation of Colorant Dispersion Liquid A

To a vessel having an inner volume of 300 L fitted with a stirrer(propeller blade) were added 20 parts (40 kg) of carbon black(Mitsubishi Carbon Black MA100S manufactured by Mitsubishi ChemicalCorporation) having an ultraviolet absorbance of toluene extract of 0.02and a true density of 1.8 g/cm³ and produced by furnace process, 1 partof 20% aqueous DBS solution, 4 parts of a nonionic surfactant (Emulgen120 manufactured by Kao Corporation), and 75 parts of ion-exchange waterhaving an conductivity of 2 μS/cm, and the whole was pre-dispersed toobtain a pigment pre-mixed liquid. The measurement of the conductivitywas carried out using a conductivity meter (a personal SC meter ModelSC72 and a detector SC72SN-11 manufactured by Yokogawa ElectricCorporation).

The volume-cumulative 50% diameter Dv₅₀ of the carbon black in thedispersion liquid after pre-mixing was about 90 μm. The above pre-mixedliquid was fed to a wet type beads mill as a raw material slurry andone-path dispersion was carried out. The inner diameter of stator wasφ75 mm, the diameter of separator was φ60 mm, and the distance betweenthe separator and disk was 15 mm. As media for dispersion, zirconiabeads having a diameter of 50 μm (true density 6.0 g/cm³) was used. Theeffective inner diameter of the stator was about 0.5 L and the packedvolume of the media was 0.35 L, so that the media-packed ratio was 70%.The rotation speed of the rotor was constant (peripheral velocity at theterminal end of the rotor was about 11 m/sec) and the above pre-mixedslurry was continuously fed at a feeding rate of about 50 L/hr by meansof a pulseless metering pump and continuously discharged from theexhaust, whereby a black colorant dispersion A was obtained. Thevolume-average particle size measured by means of microtrack UPA was 150nm and the solid matter concentration was 24.2% by weight.

Production of Mother Particle A for Development

Polymer primary particle dispersion liquid A1:

-   -   95 parts as solid matter    -   (998.2 g as solid matter)

Polymer primary particle dispersion liquid A2:

-   -   5 parts as solid matter

Colorant fine particle dispersion liquid A:

-   -   6 parts as colorant solid matter    -   20% aqueous DBS solution:    -   0.1 part as solid matter

Using the above individual components, a toner was produced by thefollowing procedure.

Into a mixing vessel (volume 12 L, inner diameter 208 mm, height 355 mm)fitted with a stirring apparatus (double helical blades), aheating/cooling apparatus, a concentrating apparatus, and amaterial/auxiliary charging apparatus were charged the polymer primaryparticle dispersion liquid A1 and the 20% aqueous DBS solution, followedby homogeneous mixing at an inner temperature of 12° C. at 40 rpm for 5minutes. Subsequently, the stirring round number was increased to 250rpm at an inner temperature of 12° C. and 0.52 part (as FeSO₄.7H₂O) of a5% aqueous ferrous sulfate solution was added over a period of 5minutes. Then, the colorant fine particle dispersion liquid A was addedover a period of 5 minutes and the whole was homogeneously mixed at aninner temperature of 12° C. at 250 rpm. Further, 0.5% aqueous aluminumsulfate solution was added dropwise under the same conditions (solidmatter in an amount of 0.10 part relative to resin solid matter).Thereafter, the inner temperature was elevated to 53° C. over a periodof 75 minutes still at 250 rpm and then to 56° C. over a period of 170minutes.

When the particle size was measured by a precise particle sizedistribution measuring apparatus (Multisizer III: manufactured byBeckman Coulter Co.; hereinafter optionally abbreviated as “Multisizer”)whose aperture diameter was 100 μm, the 50% volume diameter was 6.7 μm.

Thereafter, the polymer primary particle dispersion liquid A2 was addedthereto over a period of 3 minutes still at 250 rpm and the whole waskept for 60 minutes as it was. Immediately after the rotation number wasdecreased to 168 rpm, the 20% aqueous DBS solution (6 parts as solidmatter) was added over a period of 10 minutes and then the whole washeated to 90° C. over a period of 30 minutes still at 168 rpm and keptfor 60 minutes.

The whole was then cooled to 30° C. over a period of 20 minutes and theresulting slurry was taken out and subjected to suction filtrationthrough a No. 5C filter (No5C manufactured by Toyo Filter Paper Co.,Ltd.) by means of an aspirator. The cake remaining on the filter wastransferred to a stainless steel vessel having an inner volume of 10 Lfitted with a stirrer (propeller blade) and was homogeneously dispersedby adding 8 kg of ion-exchange water having a conductivity of 1 μS/cmand stirring at 50 rpm, followed by stirring for another 30 minutes.

Thereafter, suction filtration was again carried out through a No. 5Cfilter (No5C manufactured by Toyo Filter Paper Co., Ltd.) by means of anaspirator. The cake remaining on the filter was again transferred to astainless steel vessel having an inner volume of 10 L fitted with astirrer (propeller blade) and containing 8 kg of ion-exchange waterhaving a conductivity of 1 μS/cm and the cake was homogeneouslydispersed by stirring at 50 rpm, followed by stirring for another 30minutes. When the process was repeated five times, the conductivity ofthe filtrate was lowered to 2 μS/cm. The measurement of the conductivitywas carried out using a conductivity meter (a personal SC meter ModelSC72 and a detector SC72SN-11 manufactured by Yokogawa ElectricCorporation).

The cake thus obtained was spread on a stainless steel pad so that theheight became about 20 mm and dried in a air-blowing drier set at 40° C.for 48 hours to obtain a mother particle A for development.

Production of Toner A for Development

Into a Henschel mixer fitted with a stirrer (Z/A₀ blade) and a deflectorfacing perpendicular to the wall from the upside and having an innervolume of 10 L (diameter 230 mm, height 240 mm) was charged 100 parts(1000 g) of the mother particle A for development. Subsequently, 0.5part of silica fine particles subjected to hydrophobic treatment withsilicone oil and having a volume-average primary particle size of 0.04μm and 2.0 parts of silica fine particles subjected to hydrophobictreatment with silicone oil and having a volume-average primary particlesize of 0.012 μm were added thereto and the whole was mixed and stirredat 3000 rpm for 10 minutes and filtrated off through a 150 mesh sieve toobtain a toner A for development. A volume-average particle size of thetoner A measured by Multisizer II was 7.05 μm, Dv/Dn was 1.14, and anaverage circularity measured by FPIA 2000 was 0.963.

[Evaluation of Image Formation]

Each of the electrophotographic photoreceptors produced in Examples 203and 204 and Comparative Example 23 and the above toner A for developmentwere loaded on a black drum cartridge and a black toner cartridge for acolor printer MICROLINE Pro 9800PS-E manufactured by Oki Date Co., Ltd.,respectively, and respective cartridges were mounted on the aboveprinter.

Specification of MICROLINE Pro 9800PS-E

Four tandems

Color 36 ppm, monochrome 40 ppm

1200 dpi

Contact roller charging (imparting direct current voltage)

LED exposure

Erasing light is used

After the printer was allowed to stand in the NN environment for 8hours, halftone images were formed under the NN environment. Further,after the printer was allowed to stand in the NL environment for another8 hours, halftone images were formed under the NL environment. Then, theimages were compared. In the case where the electrophotographicphotoreceptor of Comparative Example 23 was used, decrease in halftonedensity was observed in the images formed in the NL environment.However, in the case where the electrophotographic photoreceptors ofExamples 203 and 204 were used, decrease in density was not observedeven in the images formed in the NL environment and good images wereobtained.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

The present application is based on Japanese Patent Application No.2006-077251 filed on Mar. 20, 2006, Japanese Patent Application No.2006-088867 filed on Mar. 28, 2006, Japanese Patent Application No.2006-161372 filed on Jun. 9, 2006, and Japanese Patent Application No.2006-167881 filed on Jun. 16, 2006, and the contents are incorporatedherein by reference.

Industrial Applicability

The phthalocyanine crystal of the present invention has advantages ofhigh sensitivity and little fluctuation in sensitivity for a humiditychange in a use environment. Therefore, it can be suitably used as amaterial (particularly, a charge generation substance) for solarbattery, electronic paper, electrophotographic photoreceptor, etc.

Moreover, the electrophotographic photoreceptor, electrophotographicphotoreceptor cartridge, and image-forming device of the invention canbe suitably used in various fields such as various electrophotographicdevices, e.g., copying machines, printers, fax machines, etc. in whichan electrophotographic technology is employed.

The invention claimed is:
 1. An electrophotographic photoreceptor,comprising: an electroconductive substrate and a photosensitive layerhaving a film thickness of 35±2.5 μm on the substrate, wherein ahalf-decay exposure E1/2 at a temperature of 25° C. and a relativehumidity of 50% rh satisfies an expression (1):E1/2≦0.059  (1), an absolute value of a difference in surface potentialat exposure E1/2 does not exceed 50V in an exposure range of from 0 to10 times the half-decay exposure E1/2 when a photo-induced dischargecurve at a temperature of 25° C. and a relative humidity of 50% rh iscompared with a photo-induced discharge curve at a temperature of 25° C.and a relative humidity of 10% rh, and E1/2 is exposure (μJ/cm²) oflight having a wavelength of 780 nm required for decaying an absolutevalue |V0| of a surface potential V0 of the photoreceptor from 550V to275V.
 2. An electrophotographic photoreceptor, comprising: anelectroconductive substrate and a photosensitive layer having a filmthickness of 30±2.5 μm on the substrate, wherein a half-decay exposureE1/2 at a temperature of 25° C. and a relative humidity of 50% rhsatisfies an expression (2):E1/2≦0.061  (2), an absolute value of the difference in surfacepotential at exposure E1/2 does not exceed 50V in an exposure range offrom 0 to 10 times the half-decay exposure E1/2 when a photo-induceddischarge curve at a temperature of 25° C. and a relative humidity of50% rh is compared with a photo-induced discharge curve at a temperatureof 25° C. and a relative humidity of 10% rh, and E1/2 is exposure(μJ/cm²) of light having a wavelength of 780 nm required for decaying anabsolute value |V0| of a surface potential V0 of the photoreceptor from550V to 275V.
 3. An electrophotographic photoreceptor, comprising: anelectroconductive substrate and a photosensitive layer having a filmthickness of 25±2.5 μm on the substrate, wherein a half-decay exposureE1/2 at a temperature of 25° C. and a relative humidity of 50% rhsatisfies an expression (3):E1/2≦0.066  (3), an absolute value of a difference in surface potentialat exposure E1/2 does not exceed 50V in an exposure range of from 0 to10 times the half-decay exposure E1/2 when a photo-induced dischargecurve at a temperature of 25° C. and a relative humidity of 50% rh iscompared with a photo-induced discharge curve at a temperature of 25° C.and a relative humidity of 10% rh, and E1/2 is exposure (μJ/cm²) oflight having a wavelength of 780 nm required for decaying an absolutevalue |V0| of a surface potential VO of the photoreceptor from 550V to275V.
 4. An electrophotographic photoreceptor, comprising: anelectroconductive substrate, and a photosensitive layer having a filmthickness of 20±2.5 μm on the substrate, wherein a half-decay exposureE1/2 at a temperature of 25° C. and a relative humidity of 50% rhsatisfies an expression (4):E1/2≦0.079  (4), an absolute value of a difference in surface potentialat exposure E1/2 does not exceed 50V in an exposure range of from 0 to10 times the half-decay exposure E1/2 when a photo-induced dischargecurve at a temperature of 25° C. and a relative humidity of 50% rh iscompared with a photo-induced discharge curve at a temperature of 25° C.and a relative humidity of 10% rh, and E1/2 is exposure (μJ/cm²) oflight having a wavelength of 780 nm required for decaying an absolutevalue |V0| of a surface potential V0 of the photoreceptor from 550V to275V.
 5. An electrophotographic photoreceptor, comprising: anelectroconductive substrate, and a photosensitive layer having a filmthickness of 15±2.5 μm formed on the substrate, wherein a half-decayexposure E1/2 at a temperature of 25° C. and a relative humidity of 50 %rh satisfies an expression (5):E1/2≦0.090  (5), an absolute value of a difference in surface potentialat exposure E1/2 does not exceed 50V in an exposure range of from 0 to10 times the half-decay exposure E1/2 when a photo-induced dischargecurve at a temperature of 25° C. and a relative humidity of 50% rh iscompared with a photo-induced discharge curve at a temperature of 25° C.and a relative humidity of 10% rh, and E1/2 is exposure (μJ/cm²) oflight having a wavelength of 780 nm required for decaying an absolutevalue |V0| of a surface potential V0 of the photoreceptor from 550V to275V.
 6. The electrophotographic photoreceptor of claim 1, wherein thephotosensitive layer comprises oxytitanium phthalocyanine.
 7. Theelectrophotographic photoreceptor of claim 2, wherein the photosensitivelayer comprises oxytitanium phthalocyanine.
 8. The electrophotographicphotoreceptor of claim 3, wherein the photosensitive layer comprisesoxytitanium phthalocyanine.
 9. The electrophotographic photoreceptor ofclaim 4, wherein the photosensitive layer comprises oxytitaniumphthalocyanine.
 10. The electrophotographic photoreceptor of claim 5,wherein the photosensitive layer comprises oxytitanium phthalocyanine.11. An electrophotographic photoreceptor cartridge comprising: theelectrophotographic photoreceptor of claim 1, and at least one of acharge unit for charging the electrophotographic photoreceptor, anexposure unit for exposing the charged electrophotographic photoreceptorto form an electrostatic latent image thereon, a development unit fordeveloping an electrostatic latent image formed on theelectrophotographic photoreceptor, and a cleaning unit for cleaning anupper side of the electrophotographic photoreceptor.
 12. Animage-forming device comprising: the electrophotographic photoreceptorof claim 1; a charge unit for charging the electrophotographicphotoreceptor; an exposure unit for exposing the chargedelectrophotographic photoreceptor to form an electrostatic latent imagethereon; and a development unit for developing the electrostatic latentimage.
 13. An image-forming device comprising: the electrophotographicphotoreceptor of claim 2; a charge unit for charging theelectrophotographic photoreceptor; an exposure unit for exposing thecharged electrophotographic photoreceptor to form an electrostaticlatent image thereon; and a development unit for developing theelectrostatic latent image.
 14. An image-forming device comprising: theelectrophotographic photoreceptor of claim 3; a charge unit for chargingthe electrophotographic photoreceptor; an exposure unit for exposing thecharged electrophotographic photoreceptor to form an electrostaticlatent image thereon; and a development unit for developing theelectrostatic latent image.
 15. An image-forming device comprising: theelectrophotographic photoreceptor of claim 4; a charge unit for chargingthe electrophotographic photoreceptor; an exposure unit for exposing thecharged electrophotographic photoreceptor to form an electrostaticlatent image thereon; and a development unit for developing theelectrostatic latent image.
 16. An image-forming device comprising: theelectrophotographic photoreceptor of claim 5; a charge unit for chargingthe electrophotographic photoreceptor; an exposure unit for exposing thecharged electrophotographic photoreceptor to form an electrostaticlatent image thereon; and a development unit for developing theelectrostatic latent image.